Method for Monitoring the Energy Content of a Water Storage Tank System

Abstract

A method of controlling a heat up of a hot water tank, comprising a tank, which contains water and receives incoming cold-water at a cold-water inlet and outputs heated water through a heated water outlet, the method comprising: heating the water in the tank depending on a thermal energy content calculated as a function of an actual incoming cold-water temperature measured by a cold-water temperature sensor, when a tapping event is identified. A water tank heating device and a controller system for controlling a heat up of a hot water tank depending on a thermal energy content calculated as a function of an actual incoming cold-water temperature.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 16/040,665, filed Jul. 20, 2018, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present disclosure relates to a method for monitoring the energy content of a water storage tank system.

It is noted that citation or identification of any document in this application is not an admission that such document is available as prior art to the present disclosure.

Future demand controlled grid systems need information about the energy quantity of storage systems for peak shaving and net stabilization reasons. In particular, the storage capacity of electric heated water tank systems is important for grid stabilization when considering electric energy generation from wind and solar sources.

Introducing a demand controlled water heating system makes it possible to optimize the power generation when under considering low cost power distribution and grid stability. In the future consumers can offer their water storage tank capacities to utilities to store thermal energy in times when wind and solar energy is abundant. Current state of the art is to provide an information about the temperature in a water tank using a capillary tube, which contains a heat sensitive fluid in contact with the water tank. U.S. Pat. No. 2,009,100 199 31 A1 provides information about such a system.

DE 10 2010 047 368 B3 shows a method of controlling a water storage tank heated with an electric element. The heat up time for the water storage tank is based on information about the consumer's history of withdrawal using different supercharging rates for temperature settings.

Both methods are expensive and/or not accurate in order to supply exact information about useful energy content in the water storage tank.

DE 10 2004 018 034 B4 shows a heat pump connected to a hot water storage system with a cold-water inlet in the lower part and a hot water supply in the upper section, linked by a heat exchanger. A temperature sensor is located in the lower part of the tank. Alternatively, an impeller flow meter is located in the water pipe. The sensor or flow meter triggers operation of the heat pump if the amount of tapped water is more than a defined threshold value.

SUMMARY OF THE INVENTION

Provided is a method of controlling a heat up of a hot water tank, comprising a tank, which contains water and receives incoming cold-water at a cold-water inlet and outputs heated water through a heated water outlet, a heating device and a controller system to control said heating device, the method comprising: heating the water in the tank by said heating device, depending on a thermal energy content calculated, by a control unit of said controller system, as a function of an actual incoming cold-water temperature measured with a cold-water temperature sensor of said controller system, when a tapping event is identified.

Preferably the method can comprise the steps of:

identifying, by a control circuit arrangement of said control unit, a tapping event,

measuring said incoming cold-water temperature with said cold-water temperature sensor,

receiving, by a receiving interface circuit of said control unit, an actual incoming cold-water temperature signal generated and transmitted by said temperature sensor, which represents said incoming cold-water temperature,

calculating, by said control circuit arrangement of said control unit, said thermal energy content as a function of said actual incoming cold-water temperature,

generating, by said control circuit arrangement of said control unit, an activation signal to activate a heating device depending on said thermal energy content,

transmitting, by a transmitter interface circuit of a control circuit, said activation signal to a receiver interface circuit of said heating device.

In a preferred embodiment said tapping event is identified by measuring successive incoming cold-water temperatures in successive cold-water temperature measurements with said cold-water temperature sensor and detecting a beginning of said tapping event when a difference of two successive incoming cold-water temperatures of two successive cold-water temperature measurements is more than 2° C.

Preferably, the control unit, in particular the control circuit arrangement, is configured to perform a comparison of said successive incoming cold-water temperatures to detect said tapping event.

Preferably said actual incoming water temperature is measured in an adequate time period during said tapping event, in which said actual incoming cold-water can be measured.

Said “adequate time period” describes a period in which said actual incoming cold-water temperature can be measured. Before this adequate time period, an incoming cold-water temperature can be higher or lower than said actual incoming cold-water temperature, for example caused by storing the incoming cold-water in the inlet pipe before the tapping process.

Preferably said adequate time period starts after a defined period from said beginning of said tapping event.

Preferably, said defined period is 20 seconds.

Preferably said adequate time period ends after more than 30 seconds or at or after an end of said tapping event.

Preferably, the method further comprises: comparing, by said control unit, said successive incoming cold-water temperatures, measured in a defined measuring rate, wherein said adequate time period starts when a difference of two successive incoming cold-water temperatures of two successive cold-water temperature measurements is less than 1° C.

Preferably, the method further comprises measuring successive incoming cold-water temperatures in successive cold-water temperature measurements with said cold-water temperature sensor during said adequate time period, storing said successive cold-water temperatures in a storing unit and averaging, by said control unit, said successive cold-water temperatures stored in said storing unit to obtain an averaged incoming cold-water temperature, which is used as said actual incoming cold-water temperature.

Preferably, the method further comprises determining, by said control unit, a validity of said depending on said difference, wherein said successive cold-water temperature measurements are valid if said difference is lower than a defined difference value.

Preferably, the method further comprises measuring a tank temperature, which is related to a thermal energy content, and output a tank temperature signal representative of said tank temperature with a tank temperature sensor mounted to said tank.

Provided is further a hot water tank heating system, comprising a tank to contain water with a water inlet configured for receiving incoming cold-water and a water outlet configured for allowing water heated to exit, a heating device to heat the water in the tank and a controller system with

• • a cold-water temperature sensor attached at a place and configured to measure an actual incoming cold-water temperature and to output an actual cold-water temperature signal representative of said actual incoming cold-water temperature and
  • a control unit comprising microprocessor software integrated in an electronic device,
  • wherein said control unit is configured to receive said actual cold-water temperature signal transmitted by said cold-water temperature senor, and
  • wherein said control unit is configured to identify a tapping event and to control the heating device when said tapping event is identified in order to heat water in the tank depending on a thermal energy content calculated as a function of said actual incoming cold-water temperature measured by said cold-water temperature sensor.

“Output an actual cold-water temperature signal” can preferably include generating an actual cold-water temperature signal.

Preferably, the hot water tank heating system comprises a cold-water pipe connected to the water inlet and a heated water pipe connected to the water outlet.

Preferably, the control unit comprises a control circuit arrangement, a receiver interface circuit for receiving signals and a transmitter interface circuit for transmitting signals. Preferably, the control unit further comprises a storage unit to store signals or the control unit is coupled to a storage unit to store signals.

Preferably, the hot water tank heating system comprises a tank temperature sensor mounted to said tank configured to measure a tank temperature, which is related to a thermal energy content, and output a tank temperature signal representative of said tank temperature, wherein said control unit is configured to receive said tank temperature signal transmitted by said tank temperature sensor.

In a preferred embodiment, the cold-water temperature sensor can be located proximate to said water inlet.

In a preferred embodiment, the cold-water temperature sensor can be mounted to an inner surface of said tank or an inner surface of a cold-water pipe connected to the water inlet.

In a preferred embodiment, the cold-water temperature sensor can be mounted to an outer surface of said tank or an outer surface of a cold-water pipe connected to the water inlet.

Provided is further a controller system for controlling a heat up of a hot water tank, comprising

• • a cold-water temperature sensor configured to be attached at a place of a tank, which contains water and comprises a water inlet configured for receiving incoming cold-water and a water outlet configured for allowing water heated to exit,
  • wherein said cold-water temperature sensor is configured to measure an actual incoming cold-water temperature and to output an actual cold-water temperature signal representative of said actual incoming cold-water temperature and
  • a control unit comprising microprocessor software integrated in an electronic device,
  • wherein said control unit is configured to receive said actual cold-water temperature signal transmitted by said cold-water temperature senor,
  • wherein said control unit is configured to identify a tapping event and to control a heating device when said tapping event is identified in order to heat water in the tank depending on a thermal energy content calculated as a function of an actual incoming cold-water temperature measured by said cold-water temperature sensor.

Provided is further a method of controlling a heat up of a hot water tank having a control unit where a tank temperature is measured and the tank temperature is fed into a control unit. A heating element is activated to heat up warm water in the tank when the control unit calls for heat. An incoming cold-water temperature is fed into the control unit and it generates a parameter effected by this incoming cold-water temperature. The tank temperature measured is related to the thermal energy content of the tank. The tank temperature is measured with a water temperature sensor mounted to the tank, further affecting the parameter with the tank temperature. A call for heat is processed depending on a comparison of a set point value with the parameter, which is generated from the tank temperature and the measured cold-water temperature.

Preferably, the method of controlling a heat up of a hot water tank having a control unit with a receiver interface circuit, a control circuit arrangement and a transmitter interface circuit, the method comprising the steps of:

measuring a first tank temperature of said hot water tank with a temperature sensor mounted to said hot water tank;

receiving, by said receiver interface circuit, a first tank temperature signal generated and transmitted by said temperature sensor, which represents said first tank temperature;

generating, by said control circuit arrangement, an activation signal to activate a heating device, when said control circuit arrangement calls for heat;

feeding an actual incoming cold-water temperature signal into said control circuit arrangement, wherein said actual incoming cold-water temperature signal represents an actual in-coming cold-water temperature of cold-water, which flows into said hot water tank;

generating, by said control circuit arrangement, a parameter based on said actual incoming cold-water temperature signal;

measuring a second tank temperature of said hot water tank with said temperature sensor after said incoming cold-water flowed into said hot water tank, wherein said second tank temperature is related to a thermal energy content of said hot water tank;

receiving, by said receiver interface circuit, a second tank temperature signal generated and transmitted by said temperature sensor, which represents said second tank temperature;

modifying, by said control circuit arrangement, said parameter based on said second tank temperature signal;

performing, by said control circuit arrangement, a comparison of a set point value with said parameter, which is modified based on said second tank temperature signal;

processing, by said control circuit arrangement, said activation signal depending on said comparison; and

transmitting, by said transmitter interface circuit to a receiver interface circuit of a heating device, said activation signal, which is processed depending on said comparison.

A “call for heat” can preferably be understood as a request to activate the heating device.

“Mounted to the tank” means that this sensor could be mounted inside the tank or outside the tank. If it is mounted outside the tank this sensor is especially mounted on an outer surface of the tank.

Preferably, the method comprises the steps of:

calculating, by said control circuit arrangement, an exact value of said thermal energy content as a function of a reference mass and said parameter, which is modified based on said second tank temperature signal,

wherein the step of generating, by said control circuit arrangement, said activation signal depends on whether said exact value is lower than said set point value,

wherein said control circuit arrangement generates said activation signal when said exact value is lower than the set point value.

Preferably, it is foreseen to supply permanently exact information of the energy content of the water storage tank system to a utility in order to meet the requirements of consumer comfort and the utility to save costs and stabilize the grid.

Preferably, the method comprises the step of calculating an exact value of thermal energy content as a function of reference mass and the generated parameter.

Preferably, the method comprises the step of calculating an exact value of thermal energy content as a function of reference mass and the modified parameter.

Preferably, the method comprise the step to measure the internal water temperature of the tank via an integral temperature sensor.

Preferably, the tank temperature is measured with an integral temperature sensor.

Additionally, a further embodiment describes a call for heat when the exact temperature value is less than the set point value.

Preferably, the step of activating the heating device depends on the amount of the calculated exact value.

In an embodiment, the step of activating the heating element follows when the amount of the calculated exact value is less than a specified value of thermal energy content.

Preferably, the method comprises: calculating, by said control circuit arrangement, an exact value of said thermal energy content as a function of a reference mass and said parameter, which is modified based on said second tank temperature signal, wherein the step of generating, by said control circuit arrangement, said activation signal depends on an amount of said exact value.

Preferably, the step of generating, by said control circuit arrangement, said activation signal depends on whether said amount of said exact value is lower than a specified value of thermal energy content, wherein said control circuit arrangement generates said activation signal when said amount of said exact value is less than a specified value of thermal energy content.

Further, it is preferred to calculate the exact value of thermal energy content by multiplying the reference mass parameter by a temperature rise value.

Preferably, the temperature rise is the difference between the set point temperature and the incoming cold-water temperature.

According to a further embodiment, it is described to compare the measured actual cold-water temperature signal with a previous stored cold-water temperature, to update the actual cold-water temperature signal if it is different than a previous one and to use the updated one to calculate the parameter. Therefore, the method comprises the steps of: comparing a measured actual cold-water temperature signal with a previous stored cold-water temperature; updating the stored cold-water temperature value if the measured actual cold-water temperature signal is different from the previous stored cold-water temperature; and utilizing the updated stored cold-water temperature value to calculate the parameter.

Preferably, wherein the stored cold-water temperature value is updated when the actual cold-water temperature signal is lower than the previous stored cold-water temperature.

In an embodiment, the method comprises the step of updating, if the actual cold-water temperature signal is different than a defined value.

According to a further embodiment, a step is described identifying a tapping event to detect the actual cold-water temperature in an adequate time period after a tapping begins.

According to a further embodiment, a step is described of detecting the cold-water temperature in an adequate time period, wherein an adequate time period begins after the end of an inadequate time period.

Said “inadequate time period” describes a period in which successive incoming cold-water temperatures can vary greatly. In particular, they can vary from said actual incoming cold-water temperature, for example caused by storing the incoming cold-water in the inlet pipe before the tapping process.

According to a further embodiment, a step is described for determining the inadequate time period when the time frame is exceeded.

According to a further embodiment, a step is described for determining the time frame of approximately 5 to 40 seconds, in particular 20 seconds.

In an embodiment, the adequate time period starts with the end of the inadequate time period and ends after more than 30 seconds, or at the end of the tapping event.

In an embodiment, the method comprises the step of comparison of a successive cold-water temperature with differences using the sensor temperature information and a time base.

According to a further embodiment it is described to detect the tapping begin if the difference of two successive cold-water temperature values is more than 2 K during the first time base.

According to a further embodiment, a step is described to start a first timer 1 with an inadequate time period.

According to this embodiment, it follows the step of comparison an actual cold-water temperature with a previous one to calculate a difference. If the difference is less than a special parameter, a timer two is activated to measure the actual cold-water temperature information via the temperature sensor during a time base.

According to a further embodiment there are described steps to detect, after second timer 2 is started, the incoming cold-water temperature frequently for a minimum duration between 5 to 30 seconds, in particular more than 10 seconds, to put each single following cold-water temperature value in a register, and compare the successive measured values. If a difference of less than a second parameter exists, the measurement is valid.

It is preferred to average the cold-water temperature values in the register, compare an actual averaged cold-water temperature with the former stored averaged value, and if the difference of the actual calculated value compared to the former stored value is more than 2 K, the former stored value is updated using a simple moving averaging process to avoid any jumping of values on a display.

According to a further embodiment, it is described to identify a tapping event with an adequate time period in order to detect the actual cold-water temperature by comparison of previous cold-water temperature values with the measured actual cold-water temperature signal, storing a lowest value of cold-water temperature of the previous cold-water temperature values and the cold water temperature measured actual cold-water temperature signal, and using the stored lowest value to calculate the exact value of thermal energy.

According to a further embodiment, a step is described in which the energy needs of at least one tank is provided or sent to an energy supplier.

According to this embodiment, it follows the step for utilities to sort the consumers into different energy demand classes in order to stabilize the voltage or frequency of the grid.

According to a further embodiment comprises a step that the water heating unit can be remotely controlled by the utility.

In an embodiment the usable hot water temperature range is between 30° C. to 50° C.

In an embodiment, the lowest usable hot water temperature is close to 40° C.

In an embodiment, a disinfection hot water temperature is close to 55° C., 60° C. or more.

The disinfection hot water temperature is especially activated depending on an amount of tapped water in a time period.

According to a further embodiment, the heating element is an electric heating element.

According to a further embodiment, the heating device is a heat exchanger of a heat pump or the tank is connected to a heat pump or refrigerant circuit. The heat pump is activated when the electronic device or a thermostat calls for heat.

According to a further embodiment, the content of the water heater must be tapped or renewed in a specific time period.

According to a further embodiment, the time to renew or tap the content of the tank could be three days.

According to a further embodiment the set temperature of the water in the tank is reduced to a lower temperature than 60° C., especially to 55° C. or less.

The available amount of mixed water is an important piece of information for the consumer and depends on the tank volume, mixing effect in the cold bottom of the tank below the element, and of course the expected hot water temperature and the temperature of the cold incoming water. For example, if the expected hot water temperature in the tank is 85° C. at 100-liter heated tank volume and the usable water temperature is 40° C. for 15° C. and 10° C. incoming cold-water temperature, the amount of mixed water is calculated, equation [0]:

In numbers, equation [1]:

$\begin{array}{cc}{M}_m=\frac{\mathrm{Mhw}*\left(T_{sw}-T_{cw}\right)}{T_{mw}-T_{cw}}M_m\mathrm{amount}\mathrm{of}\mathrm{mixed}\mathrm{water}T_{\mathrm{mw}}\mathrm{Mix}\mathrm{Water}\mathrm{temperature}M_{hw}\mathrm{available}\mathrm{heated}\mathrm{tank}\mathrm{volume}T_{sw}\mathrm{Expected}\mathrm{hot}\mathrm{water}\mathrm{temperature}\left(\mathrm{set}\mathrm{point}\right)T_{cw}\mathrm{Temperature}\mathrm{incoming}\mathrm{cold}\text{-}\mathrm{water}& \mathrm{Equation}\left[0\right]\\ M_{m15}=\frac{100l*\left(85-15\right)\left(°C.\right)}{40-15\left(°C.\right)}=280lM_{m10}=\frac{100l*\left(85-10\right)\left(°C.\right)}{40-10\left(°C.\right)}=250l& \mathrm{Equation}\left[1\right]\end{array}$

In this example, the amount of useful water is reduced by more than 10% if the variation of incoming cold-water is more than 5 K. A 5 K variation of the incoming cold-water temperature is a good average value if the seasonal ambient temperature between summer and winter season is taken into account.

In addition, there is a variation of the annual average incoming cold-water temperature depending on the geographic location.

In another embodiment, tank data is provided to utilities where a need of electric energy is calculated for heat up time.

With this, data from different tank systems utilities can remotely control the tanks and define the heat up start or activation of the heating device.

Herewith a load shifting is possible on the utility's grid, especially to control the network voltage or network frequency.

In a preferred embodiment the method comprises: calculating, by said control circuit arrangement, an exact value of said thermal energy content by multiplying a reference mass parameter by a temperature rise value, wherein said temperature rise value is a difference between said set point value and said actual incoming cold-water temperature, wherein the step of generating, by said control circuit arrangement, said activation signal depends on said exact value.

Preferably, the method further comprises: comparing, by said control circuit arrangement, said actual incoming cold-water temperature represented by said actual cold-water temperature signal fed into said control circuit arrangement with a previous stored water temperature represented by a previous stored water temperature signal, which is stored in a storage circuit of said control circuit arrangement; updating, by said control circuit arrangement, said previous stored water temperature signal, if said actual incoming cold-water temperature differs from said previous stored water temperature; and utilizing said stored water temperature signal, which is updated, for the step of generating, by said control circuit arrangement, said parameter.

Preferably, the step of updating, by said control circuit arrangement, said previous stored water temperature signal, depends on whether said actual incoming cold-water temperature is lower than said stored water temperature, wherein said control circuit arrangement updates said previous stored water temperature signal if said actual incoming cold-water temperature is lower than said previous stored water temperature.

Preferably, the step of updating, by said control circuit arrangement, said previous stored water temperature signal, depends on whether said actual incoming cold-water temperature is different from a defined value.

Preferably, wherein the step of feeding said incoming cold-water temperature signal into said control circuit arrangement, comprises the steps: measuring said actual incoming cold-water temperature with a cold-water temperature sensor located in said hot water tank close to a water inlet; and receiving, by said receiver interface circuit, said actual incoming cold-water temperature signal generated and transmitted by said cold water temperature sensor, which represents said actual incoming cold-water temperature.

Preferably, the method further comprises: identifying a tapping event in order to detect said actual incoming water temperature within an adequate time period after a tapping begins.

Preferably, the method further comprises: detecting said actual incoming cold-water temperature within said adequate time period.

Preferably, said adequate time period starts after a defined period from a beginning of said tapping event.

Preferably, said defined period is 20 seconds.

Preferably said adequate time period starts after a defined period from a beginning of said tapping event and ends after more than 30 seconds or at or after an end of said tapping event.

Preferably the step of detecting the actual incoming cold-water temperature within said adequate time period further comprises the steps of: measuring successive incoming cold-water temperatures in successive cold-water temperature measurements; and performing, by said control circuit, a comparison of said successive cold-water temperature measurements using differences between said successive incoming cold-water temperatures and information of a time base, which controls a measuring rate.

Preferably, the method further comprises: detecting a beginning of said tapping event when a difference of two successive incoming cold-water temperatures of two successive cold-water temperature measurements of more than 2 K results from said comparison of said successive cold-water temperature measurements.

Preferably, the method further comprises: starting a first timer at said beginning of said tapping event to detect a period after which said adequate time period starts.

Preferably, the method further comprises: comparing a last measured incoming cold-water temperature with a previously measured incoming cold-water temperature to calculate a difference; and activating a second timer, which initiates detecting said actual incoming cold-water temperature or successive incoming cold-water temperatures with a time base, when said difference is lower than a first defined difference value.

Preferably, the method further comprises: after said second timer is started, detecting successive incoming cold-water temperatures periodically for a minimum duration of more than 10 seconds and putting each incoming cold-water temperature in a register; performing, by said control circuit arrangement, a comparison of said successive incoming cold-water temperatures putted in said register; and determining, by said control circuit arrangement, a validity of said successive cold-water temperature measurements depending on a difference resulting from said comparison, wherein said successive cold-water temperature measurements are valid if said difference is lower than a second defined difference value.

Preferably, the method further comprises: averaging, by said control circuit arrangement, the successive incoming cold-water temperatures putted in said register to obtain an averaged incoming cold-water temperature; comparing, by said control circuit arrangement, said averaged incoming cold-water temperature with a previous stored averaged water temperature represented by a previous stored averaged water temperature signal, which is stored in a storage circuit of said control circuit arrangement; and updating, by said control circuit arrangement, said previous stored averaged water temperature signal, if a difference between said averaged incoming cold-water temperature and said previous stored averaged water temperature is more than 2 K, wherein the step of updating, by said control circuit arrangement, said previous stored water temperature signal comprising a simple moving averaging process.

Preferably, the method further comprises: identifying a tapping event with a adequate time period in order to detect said actual incoming water temperature by comparing, by said control circuit arrangement, previously measured incoming cold-water temperatures with an last measured incoming cold-water temperature; storing, by said storage circuit, a first temperature signal, which represents a lowest temperature of said previously measured incoming cold-water temperatures, and a second temperature signal, which represents the last measured incoming cold-water temperature; and utilizing said first temperature signal to calculate an exact value of said thermal energy content of said hot water tank.

Preferably, the method further comprises: providing energy needs of at least one hot water tank to an energy supplier or transmitting energy needs of at least one hot water tank to a utility company.

Preferably, a utility company sorting consumers into different energy demand classes in order to stabilize a voltage to keep said voltage constant, a frequency to keep said frequency constant, or both, of an electric grid.

Preferably, the heating device comprises a receiver interface circuit to receive a remote control command, which is generated and transmitted by a utility company, wherein the method comprises the step of receiving, by said receiver interface circuit of the heating device, said remote control command generated and transmitted by said utility company.

Preferably, said temperature sensor for measuring said first tank temperature and said second tank temperature of said hot water tank is mounted on an outer surface of said hot water tank.

Preferably, wherein said temperature sensor for measuring said first tank temperature and said second tank temperature of said hot water tank is mounted on an inner surface of said hot water tank.

In an aspect, the disclosure relates to a method of determining a thermal energy content of a hot water tank device, the hot water tank device comprising a tank, a cold-water inlet, a heated water outlet, a cold-water temperature sensor, a heating device and a controller component, the tank containing water, wherein the tank receives incoming cold-water at the cold-water inlet and outputs heated water through the heated water outlet when a tapping event occurs, the heated water outlet being located in an upper portion of the tank and the cold-water inlet being located in a lower portion of the tank with the heating device being thermally coupled to water in between the cold-water inlet and the heated water outlet, the cold-water temperature sensor being arranged in the lower portion of the tank configured to determine a temperature of the water in vicinity of the cold-water inlet, wherein the water within the tank is heated by operation of the heating device thermally coupled to the water, the operation of the heating device is controlled by said controller component, the method comprising: measuring, using the cold-water temperature sensor, successive incoming cold-water temperatures in successive cold-water temperature measurements measured in a defined measuring rate, detecting, by said controller component, a beginning of a tapping event when a difference of two successive incoming cold-water temperatures of two successive cold-water temperature measurements exceeds a predetermined first temperature difference threshold, measuring, using the cold-water temperature sensor, successive incoming water temperatures during an adequate time period after the beginning of said tapping event, deriving, using the controller component, the actual incoming water temperature as an average of the incoming water temperatures measured during said adequate time period, determining, using the controller component, the thermal energy content of the hot water tank device as a function of said derived actual incoming cold-water temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a relative inaccuracy of a mix water amount at different incoming cold-water temperatures.

FIG. 2 shows the average ground water temperature in the US by location.

FIG. 3 shows a water storage system.

FIG. 4 shows a water storage system with a tilted heating device.

FIG. 5 shows a water storage system with a flow sensor.

FIG. 6 shows a result of a feedback of different water heater devices.

DETAILED DESCRIPTION OF EMBODIMENTS

It is to be understood that the figures and descriptions have been simplified to illustrate elements that are relevant for a clear understanding of the present disclosure, while eliminating, for purposes of clarity, many other elements, which are conventional in this art. Those of ordinary skill in the art will recognize that other elements are desirable for implementing the present disclosure. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present disclosure, a discussion of such elements is not provided herein.

The present disclosure will now be described in detail on the basis of exemplary embodiments.

For example, in the US there is a variation of the annual average incoming water temperature by location of 40° F. as illustrated in FIG. 2. A calculation shows in case of 15° C. incoming water temperature and a full loaded tank the customer gets 280 l mixed water out of the tank. If the incoming cold-water temperature changes from 15° C. to 10° C. the amount of hot water produced with the same tank is 30 l less than the indicated value. For an accurate energy monitoring device, it is important to take a variation of incoming cold-water temperature into account or more if units are installed in a location where the temperature of the incoming cold-water temperature differs from the estimated value. In the above example, the water volume in the tank is 100 l and a set point for the water temperature in the tank is 85° C. In the context of the present disclosure, a “full loaded tank” or “full tank” is a tank for which the water temperature is heated to the expected hot water temperature, i.e. the set point of 85° C. in the above example.

The following graph FIG. 1 shows the inaccuracy of the indicated mix water amount if an estimated incoming cold-water temperature of 15° C. is considered. The example is basing on a 300-l tank with an integral sensor and 60° C. hot water temperature setting.

Referring to FIG. 1 the following is cited as an example. If the incoming water temperature is 15° C., the deviation of the displayed mixed water amount is 0.

If the tank has a load status of 0.5, that means the tank is half empty, the effective available amount of usable hot water is 20% less for 8° C. cold-water and 14% less for 10° C. incoming cold-water in comparison to the displayed amount.

If the incoming cold-water temperature is 25° C. and the tank is 50% empty, the displayed amount of mixed water is 28% less than the amount, which is actually available.

The energy monitoring system has a higher accuracy under consideration of alternating seasonal incoming cold-water temperatures, and a standard energy monitoring device is offered for different locations from northern to southern climates. The higher accuracy is established if the incoming cold-water temperature is measured using a temperature sensor which needs to be located close to the incoming cold-water inlet tube.

The embodiment describes a system, which controls the energy content of a water tank using an integral sensor, and an additional sensor located close to the incoming cold-water tube. Preferably, the additional sensor is a cold-water temperature sensor.

FIG. 3 shows schematically and exemplarily a hot water tank device, which is also referred to as a water storage system. The hot water tank device comprises a tank 1 with a hot water outlet pipe 2, an incoming cold-water inlet pipe 3, a heating device 4, an electronic device 5, a display 6 and an actuator panel 7. There is optionally a flow sensor 106 provided to measure the flow of water into the tank 1.

With this flow sensor 106 the exchange of water in the tank is measured depending on the amount of tapped water in a time period that could affect the set point temperature.

Display 6 and actuator panel 7 can be implemented as actual physical devices, for instance on the outside of the hot water tank device. Just as an example, display 6 and actuator panel 7 can comprise a touch sensitive LCD screen to integrate the functions of displaying and adjusting the device, while also all other display and actuation alternatives known in the art can be used.

Alternatively or additionally, display 6 and actuator panel 7 can be implemented remotely, for instance using a downloadable App which communicates wirelessly with electronic device 5.

There are several temperature sensors 8, 9, 10 mounted to the tank 1. The temperature sensor 8 situated close to the pipe where the hot water leaves the tank, an integral temperature sensor 9, which is mounted in a vertical direction of the tank 1 in order to create a thermocouple chain of a multiple sensor elements, and a bottom temperature sensor 10 situated close to the bottom incoming cold-water port. The electronic device 5 is connected to the heating device 4 to bring the heating device 4 into operation if the water needs to be heated. In this embodiment, the heating device is an electric heating element. In another case, it could additionally or alternatively be a heat exchanger of a heat pump or the tank 1 is connected to a heat pump or refrigerant circuit. The tank 1 preferably comprises or consists of steel, wherein also other materials are contemplated.

A safety cut-out is required to shut the heating device 4 down in case of a failed electronic control 5 or temperature sensor 8, 9, 10 failures. The safety cut-out is not shown in FIG. 3. All temperature sensors 8, 9, 10 may be mounted on the tank surface using a tape or using welded sensor sleeves which are in contact with water on well-placed spots.

The electronic device 5 in one embodiment comprises a microcontroller, which controls the amount of usable hot water in the tank 1 by controlling heating device 4. The amount of usable hot water in the tank 1 is determined using the equation [0]. The temperature difference between a temperature measured by temperature sensor 8 and a temperature set point is calculated. The temperature set point is adjustable on the actuator panel 7, for instance. The energy content of the tank 1 is recorded in energy units [KWh] and the temperature difference is determined between a measured temperature and the temperature setting. Electronic device 5 is configured to store a parameter indicating the incoming cold-water temperature. The incoming cold-water temperature is crucial for determining the amount of usable hot water in the tank 1 and also to determine the load status of the tank.

The thermal conductivity of the steel tank 1 surface and the thermal conductivity of the water transfer heat from the heated top section 101 above the heating device 4 to the cold bottom section 102 of the tank 1, such that also a cold sump 103 is heated. This creates an inaccurate measurement result of the incoming water temperature if the temperature determined by temperature sensor 10 is considered the cold-water temperature. Also, depending on the incoming cold-water pipe 3 section between the water storage tank 1 and an entrance of a pipe into a building where the water tank 1 is installed more or less heat gets transferred from the ambient conditions to the cold-water, which warms up the water in a tube section 104, cf. FIG. 4.

The actual incoming cold-water temperature needs to be detected with the following steps which are integrated in the microprocessor software as part of the electronic device 5 including an electronic main board.

1. Identify a tapping event with an adequate time period in order to detect the actual cold-water temperature by comparison of successive cold-water temperature values using the temperature information of sensor 10 and a time base of 5 seconds.

2. Tapping begin is detected if the difference of two successive cold-water temperature values determined by temperature sensor 10 is more than a defined first temperature difference threshold, for example 2 K. Start a first timer 20 when tapping begin is detected.

3. Timer 20 compares the successive measured cold-water temperature values periodically, for instance with a time base of 2 seconds. If the difference of two successive measured temperature values is less than a second temperature difference threshold, for example less than 1 K, start a second timer 21.

4. Timer 21 detects the incoming cold-water temperature periodically, for instance every 2 seconds, for a time period exceeding a minimum duration, for example a time period of more than 10 seconds, and puts each single following temperature value in a register. The storing in a register is disclosed as one example Timer 21 and 20 are running in parallel and if the comparison of successive measured values shows a difference exceeding a third temperature difference threshold, which can for instance be equal to the first temperature difference threshold such as more than 2 K, both timers are stopped and the measurement is considered not valid. This would correspond to a situation in which the temperature drop, which fell below the second temperature difference threshold, would rise again, in other words, the water temperature would again significantly drop, contrary to what is expected as a true or actual incoming cold water temperature.

5. If the measurement is considered valid, i.e. if the conditions for considering the measurement not valid in step 4 above do not apply, averaging the cold-water temperature values takes place by electronic device 5. It should be emphasized that any implementation of such averaging process as known in the art is contemplated.

6. Compare the current averaged cold-water temperature with the former stored averaged value.

7. If the difference of the actual calculated value compared to the former stored value is more than 2 K overwrite the former stored value using simple moving averaging process.

8. For initial start, a factory temperature value of 15° C. cold-water temperature is stored.

The remaining energy content Q_energy in the tank is calculated using the following law or equation [2]:

Q_energy=M_mcw*CP_Water*(T_mw−T_cw)  Equation [2]:

• • M_{m cw} amount of mixed water based on cold-water temperature
  • T_mw mix water temperature
  • CP_water specific heat capacity of water
  • T_cw temperature incoming cold-water

The energy content of the tank Q_{energy set point} is the energy content if the thermostat of the tank is satisfied. It is calculated with the following equation [3]:

$\begin{array}{cc}{Q}_{\mathrm{energyset}}=M_{m\mathrm{setpoint}}*CP_{\mathrm{Water}}*\left(T_{\mathrm{mw}}-T_{\mathrm{cw}}\right)& \mathrm{Equation}\left[3\right]\end{array}$

• • M_{m setpoint} amount of mixed water based on cold-water temperature and setpoint temperature
  • T_mw mix water temperature
  • CP_water specific heat capacity of water
  • T_cw temperature incoming cold-water

The amount of energy Q_{energy reload} needed to be recharged is calculated—equation [4]:

Q_{energy reloaded}=Q_{energy setpoint}*−Q_energy  Equation [4]:

The value of Q_{energy reload} is permanently calculated in the software of the electronic device 5.

The energy content information of the water tank is transmitted from the electronic device 5 over line 13 to a ripple control transmitter device 14, which can be connected to a structure like the internet.

For remote control, the ripple control tuner 12 is connected via line 11 to the electronic device 5. Both devices 12 and 14 may be integrated with the electronic device 5. It is an advantage to deliver the energy content signal in form of a pulse pattern in a frequency range between 110 Hz-2000 Hz.

This is an advantage because it is of interest to a grid owner to sort consumers into different energy demand classes in order to be able to stabilize the voltage of the grid structure by remote control.

FIG. 6 shows the result of feedback of different water heater devices connected with a ripple control system. Due to the loading information of each single water tank 1 system, the units get categorized in terms of their individual loading demand. For example, the number of vertical lines in category [A] represent the number of consumers who need—or are capable of receiving—a loading capacity of less than 2.5 KWh each. Those units are transmitting their loading demand via their ripple control transmitter a 110 Hz signal to the grid owner. Categories [B], [C] and [D] are categories for other loading capacity needs.

A tank 1 volume is also calculated.

A varied incoming cold-water flow is measured with a sensor.

An incoming cold-water temperature is a value, which is corresponding to the actual water temperature of the cold-water source. This value could be determined by measuring the cold-water temperature by the water utility in a water treatment facility or in a main feed line of the utility. This value is transmitted to the control unit where the energy content of the water tank is calculated. Otherwise, it is an embodiment, that the cold-water temperature is measured in a water line of the building where the water tank is located or in or at the water tank.

An embodiment of the sensor 10 is an at least single sensor element in close distance to a water inlet 104. It could be mounted inside the cold sump 103 or at the bottom of the tank 1, at the water inlet 105, outside or inside, or in the area of the tube section 104. In a special case where the incoming cold waterpipe 3 is situated through the top section 101 of the tank 1, the sensor could be applied in the area of the incoming cold-water pipe 3 or other water inlet.

An embodiment of the integral sensor 9 is a chain of thermocouples especially in line, vertically mounted, a wound wire with a defined length consisting of material with NTC or PTC characteristics, a layer with a printed sensor or a multiple printed sensor chain or at least a couple of sensors in a series or parallel circuit. The integral sensor is located inside or outside the tank 1.

Data acquisition is realized by wire or wireless communication between the temperature sensor 8, 9, 10 and the electronic device 5 or other control unit.

The temperature sensor 10 should be installed at a place of the actual cold-water temperature. This place is in another embodiment one or more representative locations where the temperature sensors 10 are located. If the temperature sensors 8, 9, 10 are mounted outside of the water tank 1 at a main water pipe or a house water pipe, it is an advantage when the temperature sensors 8, 9, 10 are connected to a wireless communication transmitter to send the measured incoming cold-water temperature to the control unit.

A further embodiment is to receive local cold-water temperature values from a utility or other source and actually store them in the electronic device 5 and to use them as cold-water temperatures instead of or in addition to a measured temperature value from the cold-water incoming sensor 10. Otherwise, a cold-water temperature value can be entered to the electronic device 5 by the user manually or via verbal command.

It is possible to retrofit existing water heating systems with this method.

While this disclosure has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure as defined in the following claims.

It is noted that citation or identification of any document in this application is not an admission that such document is available as prior art to the present disclosure.

Claims

1. A method of determining a thermal energy content of a hot water tank device, the hot water tank device comprising a tank, a cold-water inlet, a heated water outlet, a cold-water temperature sensor, a heating device and a controller component,

the tank containing water, wherein the tank receives incoming cold-water at the cold-water inlet and outputs heated water through the heated water outlet when a tapping event occurs,

the heated water outlet being located in an upper portion of the tank and the cold-water inlet being located in a lower portion of the tank with the heating device being thermally coupled to water in between the cold-water inlet and the heated water outlet,

the cold-water temperature sensor being arranged in the lower portion of the tank configured to determine a temperature of the water in vicinity of the cold-water inlet,

wherein the water within the tank is heated by operation of the heating device thermally coupled to the water, the operation of the heating device is controlled by said controller component, the method comprising:

measuring, using the cold-water temperature sensor, successive incoming cold-water temperatures in successive cold-water temperature measurements measured in a defined measuring rate,

detecting, by said controller component, a beginning of a tapping event when a difference of two successive incoming cold-water temperatures of two successive cold-water temperature measurements exceeds a predetermined first temperature difference threshold,

measuring, using the cold-water temperature sensor, successive incoming water temperatures during an adequate time period after the beginning of said tapping event,

deriving, using the controller component, the actual incoming water temperature as an average of the incoming water temperatures measured during said adequate time period,

determining, using the controller component, the thermal energy content of the hot water tank device as a function of said derived actual incoming cold-water temperature.

2. The method according to claim 1, wherein said adequate time period starts when a difference of two successive incoming cold-water temperatures of two successive cold-water temperature measurements is below a second temperature difference threshold.

3. The method according to claim 1, wherein said adequate time period ends after a predetermined period of time has elapsed or at or after an end of said tapping event.

4. The method according to claim 1, wherein the step of measuring successive incoming cold-water temperatures in successive cold-water temperature measurements with said cold-water temperature sensor during said adequate time period comprises storing said successive cold-water temperatures in a storing unit of the controller component.

5. The method according to claim 1, further comprising:

determining, by said control unit, a validity of subsequent incoming water temperature measurements during said adequate time period, wherein said subsequent cold-water temperature measurements are valid if a temperature difference between the two subsequent cold-water temperature measurements is lower than a third temperature difference threshold.

6. The method according to claim 1, the hot water tank device further comprising a second temperature sensor mounted to said tank, the method further comprising:

measuring a tank temperature using the second temperature sensor, which is related to a thermal energy content, and output a tank temperature signal representative of said tank temperature with a tank temperature sensor mounted to said tank.

7. The method according to claim 1, further comprising a step of transmitting, using a ripple control transmitter device in signal communication with the controller component, an energy content signal indicative of the determined thermal energy content.

8. The method according to claim 7, further comprising a step of receiving, using a ripple control tuner in signal communication with the controller component, a signal for activating the heating device in response to the energy content signal.

9. A hot water tank device, the hot water tank device comprising a tank, a cold-water inlet, a heated water outlet, a cold-water temperature sensor, a heating device and a controller component,

the tank containing water, wherein the tank receives incoming cold-water at the cold-water inlet and outputs heated water through the heated water outlet when a tapping event occurs,

the heated water outlet being located in an upper portion of the tank and the cold-water inlet being located in a lower portion of the tank with the heating device being thermally coupled to water in between the cold-water inlet and the heated water outlet,

the cold-water temperature sensor being arranged in the lower portion of the tank configured to determine a temperature of the water in vicinity of the cold-water inlet,

wherein the water within the tank is heated by operation of the heating device thermally coupled to the water, the operation of the heating device is controlled by said controller component,

the cold-water temperature sensor being configured to successively measure incoming cold-water temperatures in successive cold-water temperature measurements in a defined measuring rate,

the controller component being configured to determine a beginning of a tapping event when a difference of two successive incoming cold-water temperatures of two successive cold-water temperature measurements exceeds a predetermined first temperature difference threshold,

the cold-water temperature sensor being further configured to successively measure incoming water temperatures during an adequate time period after the beginning of said tapping event,

the controller component being configured to derive the actual incoming water temperature as an average of the incoming water temperatures measured during said adequate time period, and

the controller component being configured to determine the thermal energy content of the hot water tank device as a function of said derived actual incoming cold-water temperature.

10. A controller system for controlling a heat up of a hot water tank, comprising

a cold-water temperature sensor configured to be attached at a place of a tank, which contains water and comprises a water inlet configured for receiving incoming cold-water and a water outlet configured for allowing water heated to exit,

wherein said cold-water temperature sensor is configured to measure an actual incoming cold-water temperature and to output an actual cold-water temperature signal representative of said actual incoming cold-water temperature and

a control unit comprising microprocessor software integrated in an electronic device,

wherein said control unit is configured to receive said actual cold-water temperature signal transmitted by said cold-water temperature senor,

wherein said control unit is configured to identify a tapping event and to control a heating device when said tapping event is identified in order to heat water in the tank depending on a thermal energy content calculated as a function of an actual incoming cold-water temperature measured by said cold-water temperature sensor.

11. A method of controlling a heat up of a hot water tank having a control unit with a receiver interface circuit, a control circuit arrangement and a transmitter interface circuit, the method comprising the steps of:

measuring a first tank temperature of said hot water tank with a temperature sensor mounted to said hot water tank;

receiving, by said receiver interface circuit, a first tank temperature signal generated and transmitted by said temperature sensor, which represents said first tank temperature;

generating, by said control circuit arrangement, an activation signal to activate a heating device, when said control circuit arrangement calls for heat;

feeding an actual incoming cold-water temperature signal into said control circuit arrangement, wherein said actual incoming cold-water temperature signal represents an actual incoming cold-water temperature of cold-water, which flows into said hot water tank;

generating, by said control circuit arrangement, a parameter based on said actual incoming cold-water temperature signal;

measuring a second tank temperature of said hot water tank with said temperature sensor after said incoming cold-water flowed into said hot water tank, wherein said second tank temperature is related to a thermal energy content of said hot water tank;

receiving, by said receiver interface circuit, a second tank temperature signal generated and transmitted by said temperature sensor, which represents said second tank temperature;

modifying, by said control circuit arrangement, said parameter based on said second tank temperature signal;

performing, by said control circuit arrangement, a comparison of a set point value with said parameter, which is modified based on said second tank temperature signal;

processing, by said control circuit arrangement, said activation signal depending on said comparison; and

transmitting, by said transmitter interface circuit to a receiver interface circuit of a heating device, said activation signal, which is processed depending on said comparison.

12. The method according to claim 11, further comprising:

calculating, by said control circuit arrangement, an exact value of said thermal energy content as a function of a reference mass and said parameter, which is modified based on said second tank temperature signal,

wherein the step of generating, by said control circuit arrangement, said activation signal depends on at least one of a) whether said exact value is lower than said set point value and b) on an amount of said exact value,

wherein said control circuit arrangement generates said activation signal when said exact value is lower than the set point value.

13. The method according to claim 11,

wherein the step of generating, by said control circuit arrangement, said activation signal depends on whether said amount of said exact value is lower than a specified value of thermal energy content,

wherein said control circuit arrangement generates said activation signal when said amount of said exact value is less than a specified value of thermal energy content.

14. The method according to claim 11, further comprising:

calculating, by said control circuit arrangement, an exact value of said thermal energy content by multiplying a reference mass parameter by a temperature rise value,

wherein said temperature rise value is a difference between said set point value and said incoming cold-water temperature,

wherein the step of generating, by said control circuit arrangement, said activation signal depends on said exact value.

15. The method according to claim 11, further comprising:

comparing, by said control circuit arrangement, said actual incoming cold-water temperature represented by said actual cold-water signal fed into said control circuit arrangement with a previous stored water temperature represented by a previous stored water temperature signal, which is stored in a storage circuit of said control circuit arrangement;

updating, by said control circuit arrangement, said previous stored water temperature signal, if said actual incoming cold-water temperature differs from said previous stored water temperature; and

utilizing said stored water temperature signal, which is updated, for the step of generating, by said control circuit arrangement, said parameter,

wherein the step of updating, by said control circuit arrangement, said previous stored water temperature signal, depends on whether said actual incoming cold-water temperature is lower than said stored water temperature,

wherein said control circuit arrangement updates said previous stored water temperature signal if said actual incoming cold-water temperature is lower than said previous stored water temperature.

16. The method according to claim 11,

wherein the step of feeding said incoming cold-water temperature signal into said control circuit arrangement, comprises the steps:

measuring said actual incoming cold-water temperature with a cold-water temperature sensor located in said hot water tank close to a water inlet; and

receiving, by said receiver interface circuit, said actual incoming cold-water temperature signal generated and transmitted by said cold water temperature sensor, which represents said actual incoming cold-water temperature.

17. The method according to claim 11, further comprising:

comparing a last measured incoming cold-water temperature with a previously measured incoming cold-water temperature to calculate a difference; and

activating a second timer, which initiates detecting said actual incoming cold-water temperature or successive incoming cold-water temperatures with a time base, when said difference is lower than a first defined difference value,

after said second timer is started, detecting successive incoming cold-water temperatures periodically for a minimum duration of more than 10 seconds and putting each incoming cold-water temperature in a register;

performing, by said control circuit arrangement, a comparison of said successive incoming cold-water temperatures putted in said register;

determining, by said control circuit arrangement, a validity of said successive cold-water temperature measurements depending on a difference resulting from said comparison, wherein said successive cold-water temperature measurements are valid if said difference is lower than a second defined difference value;

averaging, by said control circuit arrangement, the successive incoming cold-water temperatures putted in said register to obtain an averaged incoming cold-water temperature;

comparing, by said control circuit arrangement, said averaged incoming cold-water temperature with a previous stored averaged water temperature represented by a previous stored averaged water temperature signal, which is stored in a storage circuit of said control circuit arrangement; and

updating, by said control circuit arrangement, said previous stored averaged water temperature signal, if a difference between said averaged incoming cold-water temperature and said previous stored averaged water temperature is more than 2° C.,

wherein the step of updating, by said control circuit arrangement, said previous stored water temperature signal comprising a simple moving averaging process.

18. The method according to the claim 11, further comprising:

providing energy needs of at least one hot water tank to an energy supplier or transmitting energy needs of at least one hot water tank to a utility company.

19. The method according to claim 11,

wherein a utility company sorting consumers into different energy demand classes in order to stabilize a voltage to keep said voltage constant, a frequency to keep said frequency constant, or both, of an electric grid.

20. The method according to claim 19,

wherein the heating device comprises a receiver interface circuit to receive a remote control command, which is generated and transmitted by a utility company,

wherein the method comprises the step of receiving, by said receiver interface circuit of the heating device, said remote control command generated and transmitted by said utility company.