Device and Method for Heating a Pumped Fluid

Abstract

This system relates to a heat transfer system utilized to transfer heat away from a fluid circulation pump for the purposes of cooling the pump and heating the pumped fluid and is especially useful for heating the water of a swimming pool using a water cooled filtration pump.

Description

FIELD

The present system relates to heat transfer systems. More specifically, this system relates to a heat transfer system utilized to transfer heat away from the pump motor of a fluid circulation pump for the purposes of cooling the pump motor and heating the pumped fluid and is especially useful for heating the water of a swimming pool or spa using a water cooled filtration pump motor.

BACKGROUND

Pumps used to move fluids can generate significant heat due to the load on their motors. This heat is generally vented to the environment or transferred to a fluidic heat exchanger. The transfer of heat to the environment, while unavoidable in some applications, is inefficient since the loss of heat is the loss of energy. If some of the heat generated by the pump motor can be captured and used beneficially, the increase in efficiency would yield economic benefits and result in a more environmentally friendly system.

One application that can benefit from the capture and use of pump motor heat is the heating of swimming pool water using a water-cooled filtration pump using pool water recirculated back to the swimming pool after it flows through a fluidic heat exchanger contained within the pump motor housing. Heating a swimming pool in this manner is not only cost effective and is a more environmentally friendly way to heat a swimming pool, but can effectively extend the swimming season without significant expense from the use of additional energy resources, the purchase of expensive heaters, and significant installation costs. Extending the swimming season for swimmers in extreme northern and southern latitudes is exceptionally helpful since the further one gets from the equator, the shorter the swimming season becomes due to the increasingly indirect angle of sunlight which is less effective at heating a body of water and the colder air which acts to cool the water at night.

Heating of swimming pool water is often accomplished using natural gas and electric heating elements, both of which are costly to operate and maintain, and must typically be incorporated into the swimming pool design at initial construction. It would be advantageous to simply retrofit an existing pool with a cost effective, quiet system to heat pool water. It would also be advantageous if the retrofitted water heating system had a neutral carbon footprint on the environment and a neutral economic impact on the operator.

SUMMARY

The disclosed system replaces the air-cooled swimming pool circulating pump motor commonly found in swimming pool installations with a water-cooled pump motor and provides a water pickup and discharge pathway for the pool water used to cool the pump motor. Ideally, the water temperature of the swimming pool is monitored by a temperature sensing means such as a thermocouple or infrared sensor so that a control means can adjust the residence time in the system to discharge sufficiently heated water. Alternatively, the pump could be a hybrid air-cooled and water-cooled pump motor controlled by a control means so as to cycle between cooling the pump with air and water to provide better control of the swimming pool temperature and allow the pump motor to operate without affecting the water temperature. Optionally, the system can be combined with a solar blanket for further efficiencies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a perspective view of a prior art swimming pool system disclosing an air cooled circulating pump.

FIG. 2 depicts a perspective view of the swimming pool heating system of a disclosed first embodiment incorporating a hybrid air/water-cooled circulating pump.

FIG. 3 depicts a perspective view of the swimming pool heating system of a disclosed second embodiment incorporating an electronic system for sensing and controlling the hybrid air/water-cooled circulating pump.

FIG. 4 depicts a local perspective view, taken at view arrow 4 of FIG. 3, of disclosed manually slide able covers for selectively covering the heat-emitting vents disposed on the pump housing.

FIG. 5 depicts a local perspective view, similar to FIG. 4, of a disclosed alternate vent-covering embodiment incorporating an articulating ring.

FIG. 6 depicts an exploded perspective view of an alternate, heat exchanging embodiment, incorporating a heat exchanger tube in a serpentine configuration winding across a conduction wall, surrounding a fluid pump motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, the prior art flow system incorporates a fluid pump 20 having an electrical motor 40. The pump motor 40 generates heat, which can be captured and utilized instead of wasted, when operating the pump 20 due to the load placed on the pump motor 40. Filtration of a fluid 1 stored in a fluid reservoir 3, e.g. a swimming pool or tank, is commonly achieved by a filter 11, e.g. a mesh screen or basket, enclosed within a pump filtration housing 10 which receives a fluid 1 pumped from a fluid reservoir 3 through a fluid intake conduit 5 to a pump filtration housing inlet 15 and subsequently exits through a pump filtration outlet 16. The fluid intake conduit 5 possesses a reservoir end 13 submerged within said fluid 1 in the fluid reservoir 3. Preferably the fluid 1 passes through a coarse filter prior to entry into the pump 20 through the pump inlet 25 to prevent clogging and/or damage to the pump 20. Some applications, circulation of swimming pool or hot tub water, require that the fluid also pass through a purification filter. The heat generated by air-cooled pump motors 40 is generally lost to the environment through a plurality of vents 44 in the pump motor housing 42. The vents 44 allow the heated air from the pump motor housing 42 to escape while permitting cooler air to enter as a means to regulate the operating temperature and prevent overheating so as to extend the life of the pump motor 40 and provide better control over the pump motor 42 temperature.

Turning now to FIG. 2, the fluid reservoir heating system 100 incorporate a preferred embodiment, pump motor 40 which utilizes a fluidic heat exchanger 50 in combination with vents with articulable covers to cool the pump motor 40. Alternative embodiments only employ fluidic cooling of the pump motor 40. A fluidic heat exchanger 50 is arranged in close association with the pump motor 40. Fluid 1 is circulated through the fluidic heat exchanger 50 by directing at least part of the fluid 1 pumped from the fluid reservoir 3 through the fluidic heat exchanger supply conduit 56 into a fluidic heat exchanger 50 and subsequently removing the fluid 1 and thermal energy through a fluidic heat exchanger drain conduit 58. The fluid 1 pumped to the fluidic heat exchanger 50 is preferably extracted from the filtered fluid 1 in the fluid transmission conduit 7. At least one flow control valve 4 controls the flow from the pump exit 16, or alternatively the fluid transmission conduit 7 or both, to a fluidic heat exchanger supply conduit 56 which couples with the fluidic heat exchanger inlet 54. A flow control valve 4 placed in the fluidic heat exchanger bypass conduit 90 is used to control the flow of fluid 1 bypassing the fluidic heat exchanger 50. The pump motor 40 transfers at least part of the heat it generates to the fluid 1 resident within the fluidic heat exchanger 50. Exemplary embodiments utilize a water cooled pump motor 40 with no air vents and a water and air cooled pump motor 40.

Continuing with FIG. 2, as the heated fluid 1 exits the fluidic heat exchanger 50, heat transferred to the fluid 1 from the pump motor 40 is removed and conducted away from the pump motor 40 and into a fluid transmission conduit 7 to be returned to the fluid reservoir 3. Cool fluid 1 subsequently flows into the fluidic heat exchanger 50 to replace the discharged heated fluid 1 and continue the process of extracting heat from the pump motor 40 for subsequent return to the fluid reservoir 3. The return of the fluid 1 heated in the fluidic heat exchanger 50 to the fluid reservoir 3 incrementally increases the temperature of the fluid 1 within the fluid reservoir 3.

Turning now to FIG. 3, the rate of temperature change can be controlled manually by adjusting the flow control valve 4 or valves 4 to vary the rate of fluid 1 flow through the fluidic heat exchanger 50, but is preferably controlled by an electronic embodiment of the control system 70 using feedback from temperature measurement sensors 72 such as infrared thermometers, laser thermometers, or temperature transducers, e.g. thermocouples, thermistors, resistance temperature detectors, and integrated circuit sensors. In a manual embodiment of the control system 70, the temperature can be read by an operator or physically sensed by touch to provide temperature feedback and allow the operator to act as the manual control system and make manual adjustments to flow rates to achieve a target fluid 1 temperature.

As best seen in FIG. 3, at least one temperature measurement sensor 72 is placed within the fluid reservoir 3. Temperature measurement sensors 72 are placed within the fluid intake conduit 5 and/or the fluid transmission conduit 7. Additionally, temperature measurement sensors 72 may be placed within the fluidic heat exchanger supply conduit 56 and the fluidic heat exchanger drain conduit 58. Measuring the temperature difference of the fluid 1 before and after the heat exchanger 50 provides quantitative feedback on the amount of heat being transferred away from the pump motor 40 by the fluid 1 and permits the control system 70 to adjust the flow control valves 4 accordingly to achieve the target fluid 1 temperature.

Various embodiments employ a flow sensor 74 to quantify the fluid flow through the fluidic heat exchanger 50 for further adjustment of the flow control valves 4. In various alternative embodiments, pressure sensors 76 are installed before and alternatively before and after the fluidic heat exchanger 50 and/or filter to detect fouling/plugging.

The electronic control system 70 utilizes programmed instructions which utilize feedback from the various sensors, e.g. temperature 72, flow rate 74, and pressure 76, to control the flow of fluid 1 through the fluidic heat exchanger 50 in an effort to achieve a target fluid 1 temperature. Preferably, the control system 70 possesses a display 80, such as an LCD screen, or a switch, such as a button or rheostat type control, which permits a target temperature to be selected. The control system 70 preferably controls the flow control valve(s) 4 to adjust the flow of fluid 1 through the fluidic heat exchanger 50. Alternatively, the control system 70 can control the flow of fluid 1 and/or the heat available for exchange by affecting the speed of the fluid pump 20.

Using feedback from the temperature sensor(s) 72, the fluid pump 20 speed and/or flow control valve(s) 4 can be adjusted to affect the rate of heating through adjustments of residence time within the fluidic heat exchanger 50 and/or increasing workload on the fluid pump 20 so as to generate more heat to be transferred away from the pump motor 40 back to the fluid reservoir 3.

As shown in FIG. 4, the pump motor housing 42 possesses vents 44 for air cooling of the pump motor 40. The vents 44 are preferably coverable by an articulable vent cover(s) 46 to provide further control of the temperatures inside the pump motor housing 42. The vents 44 can be opened for running the pump motor 40 at a cooler temperature or simply used to provide cooling when the flow through the fluidic heat exchanger 50 is discontinued or minimized to reduce or discontinue the heating of the fluid 1 in the reservoir 3. Ideally, the articulable vent cover(s) 46 is controlled by the control system 70 to optimize the temperature within the pump motor housing 42, provide better control over the rate of fluid 1 heating, and to stabilize the fluid 1 temperature.

A beneficial example of the method of heating a circulating fluid 1 using waste heat from the fluid pump motor 40 is the heating of swimming pool, hot tubs, and spa water. Swimming pools undergo frequent or almost continuous filtration. The pool water is typically drawn from the pool through a basket filter 11 before entering the pump 20 and subsequently being returned to the pool after passing through a purification filter. The pump motor 40 generates significant heat which is vented to the environment through air vents 44 in the pump motor housing 42. Capturing the waste heat by redirecting at least part, and potentially all of the filtered recirculated pool water back to the pump 20 for use in a fluidic heat exchanger 50 which transfers heat from the pump motor 40 serves to both cool the pump motor 40 and heat the pool water.

Yet another example is the use of the system to heat a fluid, such as lubricant or base oil, as it is transferred from an outside tank to an indoor switching and pumping area for filling of packaging or blending with additional components. The lubricant or base oil could undergo gelation or significant wax crystal formation which would prevent transfer of the fluid or cause pump failure due to cavitation and the creation of a vacuum within a transfer line. Heating of the lubricant or base oil could improve cold temperature pumpability without requiring mechanical breakup of cold induced gels or wax crystal formations or the application of electrical heating jackets to transfer lines.

The water in swimming pools is typically heated by solar radiation. The rate of heating can be increased by the use of a common solar blanket. The use of a solar blanket in combination with the system 100 and method detailed above increases the rate of heating and decreases heat loss resulting from evaporation or direct contact with the cool night air. Other methods of heating the water in swimming pools include natural gas and electric heaters, both of which consume increasingly scarce natural resources. The disclosed system 100 and method have the advantage of being carbon neutral. The system 100 also eliminates much of the expense of retrofitting swimming pools without preexisting heating systems since replacing the pump motor 40, routing the fluid 1 through a fluidic heat exchanger 50 and its associated inlet 54 and outlet conduits 52, and placing the sensors 72, 74 and 76 is all that is required.

The use of sensors 72, 74 and 76 allows the use of a closed loop control system 70 or feedback controller 70. Preferably, the sensor 72, 74 and 76 outputs are fed back through to the control system 70 for comparison to a reference value. The control system 70 can be arranged as a single-input-single-output, i.e. SISO, control system or as a multi-input-multi-output, i.e. MIMO, control system. A preferred feedback control design is the PID controller, i.e. proportional-integral-differential controller. If u(t) is the control signal sent to the system, y(t) is the measured output and r(t) is the desired output, and the tracking error is e(t)=r(t)−y(t), a PID controller has the general form:

$u\left(t\right)=\mathrm{MV}\left(t\right)=K_pe\left(t\right)+K_i{\int }_0^te\left(\tau \right)\tau +K_d\frac{}{t}e\left(t\right)$

wherein:
K_p: Proportional gain
K_i: Integral gain
K_d: Derivative gain

t: Time.

A PID controller calculates an error value as the difference between a measured process variable and a desired set point. The PID controller attempts to minimize the error by adjusting the process control inputs. The PID controller is preferably controlled by commercially available PID tuning and loop optimization software. Alternatively, a PI controller, i.e. proportional-integral controller, is used. A PI controller is similar to a PID controller, but without using a derivative of the error. A PI controller is useful to keep the fluid 1 temperature steady when sensor data is noisy.

As best seen in FIG. 5, the fluid 1 temperature can be controlled manually by repositioning the vent cover 57 relative to the air vents for the hybrid air cooled/water cooled pump motor 40. The vent cover(s) 57 is preferably controlled by the control system 70 in response to temperature data collected by the previously discussed temperature sensors. In an alternative embodiment the vent cover 57 is actuated by a solenoid or similar means and slides or rotates into place over the pump motor housing 42 to cover the vents 44 as desired. In a still further embodiment, the fluid 1 temperature can be controlled manually by adjusting the flow rate through the fluidic heat exchanger 50 that cools the pump motor 40 in the water cooled pump motor 40 or in the hybrid air cooled/water cooled pump motor 40 by adjusting the flow control valve(s) 4 arranged before and/or after the fluidic heat exchanger 50. Adjusting the volumetric rate of the pump 20 also provides a way to control the temperature of the fluid 1 since increasing the load on the pump 20 would yield more thermal energy for recapture and transfer to the fluid reservoir 3 or swimming pool by way of the fluidic heat exchanger 50.

While the internal configuration of the fluidic heat exchanger may take a number of configurations, FIG. 6 shows a preferably tubular passage winding across a fluidic heat exchanger conduction wall 55 of the fluidic heat exchanger 50 that is in contact or close proximity with the pump motor 40 within the pump motor housing 42. Inside the fluidic heat exchanger 50, the fluid 1 flow is either turbulent or laminar. Turbulent flow produces better heat transfer, due to the mixing of the fluid 1 which results in better dispersion of the heat throughout the fluid 1. Laminar-flow heat transfer relies entirely on the thermal conductivity of the fluid 1 to transfer heat from inside a stream to a fluidic heat exchanger 50 wall. An exchanger's fluid 1 flow can be determined from its Reynolds number (NRe):

$N_{\mathrm{Re}}=\frac{\rho \times V\times D}{\mu }$

Where V is flow velocity and D is the diameter of a tube in which the fluid flows. The units cancel each other, making the Reynolds number dimensionless. If the Reynolds number is less than 2,000, the fluid flow will be laminar; if the Reynolds number is greater than 6,000, the fluid flow will be fully turbulent. The transition region between laminar and turbulent flow produces rapidly increasing thermal performance as the Reynolds number increases. The type of flow determines how much pressure a fluid loses as it moves through a heat exchanger. This is important because higher pressure drops require more pumping power which affect pump operating conditions and may require a larger pump than would commonly be used in a particular pumping application.

Laminar flow produces the smallest loss, which increases linearly with flow velocity. For example, doubling the flow velocity doubles the pressure loss. For Reynolds numbers beyond the laminar region, the pressure loss is a function of flow velocity raised to a power in the range 1.6-2.0. In other words, doubling the flow could increase the pressure loss by a factor of four. The pressure loss is accounted for in the selection of the appropriate pump and is a skill known to those skilled in the art of fluid mechanics. In embodiments incorporating air vents 44 in the pump motor housing 42, the fluidic heat exchanger is configured and arranged so as to not block the vents 44 or otherwise interfere with their function.

It is the inventor's intention that, although numerous alternative embodiments may be derived from this disclosure by those seeking to understand and replicate the inventor's system and method, such configurations that do not stray from the principles disclosed and claimed herein are not disclaimed but should be viewed as equivalents which also fall within the patent claims of the inventor.

Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Claims

1. A heating system for pumped fluids comprising:

a. a pump, said pump having a pump motor, a pump motor housing, pump inlet, a pump outlet, and a fluidic heat exchanger, wherein said pump motor is arranged in close proximity with said fluidic heat exchanger, said fluidic heat exchanger possessing at least one fluidic heat exchanger inlet and at least one fluidic heat exchanger outlet;

b. at least one fluid retrieval conduit for the transmission of a fluid to said pump, said fluid retrieval conduit having a fluid retrieval end and a pump end;

c. at least one fluid transmission conduit which functions to transmit said fluid drawn by and through said pump to a point past said pump

d. a heat exchanger inlet conduit to conduct at least some of said fluid from said pump outlet to said fluidic heat exchanger inlet; and

e. a fluidic heat exchanger outlet conduit to conduct said fluid from said fluidic heat exchanger to said fluid transmission conduit.

2. The heating system of claim 1, wherein said heating system possesses a means to control said heating system, said means to control said system being selected from the group consisting of manual and electronic control systems.

3. The heating system of claim 1, further comprising at least one fluidic heat exchanger flow control valve which controls the rate of flow of said fluid through said fluidic heat exchanger, wherein a flow rate of said flow valve is controlled by said means to control.

4. The heating system of claim 3, wherein said pump motor housing possesses at least one air vent and at least one moveable air vent cover.

5. The heating system of claim 4, wherein said at least one air vent cover is moved by said means to control so as to allow at least part of said vent to be covered and inhibit air cooling of said pump motor.

6. The heating system of claim 3, further comprising at least one temperature sensor.

7. The heating system of claim 6, wherein said at least one temperature sensor is selected from the group consisting of contact and non-contact sensors.

8. The heating system of claim 7, wherein said at least one temperature sensor is arranged to measure a temperature of said fluid within a fluid transmission circuit.

9. The heating system of claim 8, wherein said temperature of said fluid is sensed within said fluid transmission conduit.

10. The heating system of claim 8, wherein said flow rate of said flow valve is modified by said control means in response to said temperature of said fluid.

11. The heating system of claim 10, wherein said fluid transmission circuit originates and ends at a fluid reservoir.

12. The heating system of claim 11, wherein said the temperature of said fluid is sensed within said fluid transmission conduit.

13. The heating system of claim 2, wherein said control system is electronic and possesses programmed instructions, a machine readable memory for storing said programmed instructions, a display, a user interface and a means for processing said programmed instructions read from said machine readable memory.

14. The heating system of claim 13, wherein said user interface of said control system allows a user to input a desired fluid reservoir temperature for use by said control system in controlling said heating system.

15. The heating system of claim 14, wherein said control system is programmed to achieve a desired fluid temperature in said fluid transmission conduit by calculating optimal values for system variables comprised of the group consisting of pump speed, fluidic heat exchanger flow rate, and the position of at least one air vent cover relative at least one said air vent.

16. The heating system of claim 15, wherein said speed of said pump, said flow rate through said fluidic heat exchanger, and said position of said at least one air vent cover are controlled by said control system in response to said calculations.

17. A heating system for pumped fluids comprising:

a. a pump, said pump having a pump motor, a pump motor housing, pump inlet, a pump outlet, and a fluidic heat exchanger, wherein said pump motor is arranged in close proximity with said fluidic heat exchanger, said fluidic heat exchanger possessing at least one fluidic heat exchanger inlet and at least one fluidic heat exchanger outlet;

b. at least one fluid retrieval conduit for the transmission of a fluid to said pump, said fluid retrieval conduit having a fluid retrieval end and a pump end;

c. at least one fluid transmission conduit which functions to transmit said fluid drawn by and through said pump to a point past said pump.

d. a heat exchanger inlet conduit to conduct at least some of said fluid from said pump outlet to said fluidic heat exchanger inlet;

e. a fluidic heat exchanger outlet conduit to conduct said fluid from said fluidic heat exchanger to said fluid transmission conduit;

f. a means to control said heating system, said means to control said system being selected from the group consisting of manual and electronic control systems.

g. a flow valve to control a flow rate of said fluid through said fluidic heat exchanger, wherein a flow rate of said flow valve is controlled by said means to control;

h. The heating system of claim, wherein said pump motor housing possesses at least one air vent and at least one moveable air vent cover moved by said means to control so as to allow at least part of said vent to be covered and inhibit air cooling of said pump motor.

18. The heating system of claim 17, wherein said fluid heat exchanger possesses tubular channels for directing said fluid along a heat exchanger conduction wall adjacent to said pump motor.

19. The heating system of claim 17, further comprising at least one temperature sensor.

20. The heating system of claim 19, wherein said at least one temperature sensor is selected from the group consisting of contact and non-contact sensors.

21. The heating system of claim 20, wherein said at least one temperature sensor is arranged to measure the temperature of said fluid within a fluid transmission circuit.

22. The heating system of claim 21, wherein said at least one temperature sensor arranged to measure the temperature of said fluid within said fluid transmission conduit.

23. The heating system of claim 20, wherein said flow rate of said flow valve is modified by said control means in response to said at least one temperature sensor.

24. The heating system of claim 23, wherein said fluid transmission circuit originates and ends at a fluid reservoir.

25. The heating system of claim 24, wherein said at least one temperature sensor is arranged to measure the temperature of said fluid within said fluid transmission conduit.

26. The method of heating a body of fluid by pumping said fluid from a fluid reservoir, through a pump which directs at least part of said pumped fluid through a fluidic heat exchanger arranged to transfer heat from a pump motor to said fluid, then returning said fluid directed through said fluidic heat exchanger back to said fluid reservoir.

27. The method of claim 26, wherein said pump further consists of a pump housing possessing at least one air vent and at least movable one air vent cover, wherein said at least one air vent cover can be moved to restrict air flow through said at least one air vent for the purpose of increasing the temperature of said pump motor within said pump motor housing so as to direct more heat to said fluid within said fluidic heat exchanger.

28. The method of claim 26, wherein said fluid reservoir is a swimming pool.

29. The method of claim 28, wherein said pump is a swimming pool filtration pump.