Abstract: A control procedure operates an expansion valve of an air conditioning system. The control procedure utilizes a first control procedure to bring a calculated superheat value within a range of a target superheat value, and a second control procedure to cause the calculated superheat value to match the target superheat value. Both the first and second control procedures preferably use Proportional, Integral, Derivative control algorithms.

Abstract: A climate control system is provided and may include a compressor, a first heat exchanger in fluid communication with the compressor, a second heat exchanger in fluid communication with the compressor and the first heat exchanger, and a third heat exchanger disposed between the first heat exchanger and the second heat exchanger. A conduit may be fluidly coupled to the third heat exchanger and the compressor and may selectively supply fluid to the compressor. A valve may control a volume of fluid supplied to the compressor via the conduit and a controller may control the valve based on a discharge temperature of the compressor and a super heat temperature of the third heat exchanger.

Abstract: A refrigerant system comprising a compressor, a condenser, an electronic expansion valve, and an evaporator is controlled in a normal operating mode to meet moderate cooling loads; however, when the load approaches that which is sufficient to induce liquid refrigerant carryover from the evaporator to the compressor, the system is controlled in a capped operating mode to limit a certain thermodynamic variable rather than controlled to meet the high load. In the normal mode, the compressor and/or the expansion valve might be controlled in response to the amount of superheat of the refrigerant leaving the evaporator or the level of liquid refrigerant in the evaporator. In the capped operating mode, the compressor and/or the expansion valve might be controlled to limit a variable such as the compressor's capacity, the saturated pressure or dynamic pressure of the refrigerant entering the compressor, or the refrigerant's mass flow rate.

Abstract: Heating equipment, including a first heat exchanger, a compressor, a second heat exchanger, and a first expansion valve that decompresses a refrigerant flowing from the second heat exchanger to the first heat exchanger, are connected so as to circulate the refrigerant. A third heat exchanger provides heat of the refrigerant flowing from the second heat exchanger to the first heat exchanger to the refrigerant flowing from the first heat exchanger toward the compressor. An injection circuit merges part of the refrigerant flowing from the second heat exchanger to the first heat exchanger with the refrigerant that is sucked by the compressor. An injection expansion valve is installed in the injection circuit and decompresses the refrigerant flowing in the injection circuit. A fourth heat exchanger is installed in the injection circuit to supply heat of the refrigerant flowing from the second heat exchanger toward the first heat exchanger to the refrigerant flowing in the injection circuit.

Abstract: A degree-of-superheat control unit (44) is configured to adjust the degree of opening of an indoor expansion valve (26) based on a control gain for determining an opening-degree adjustment amount of the indoor expansion valve (26), and includes a control-gain determination unit (41) configured to increase a control gain g when the target-degree-of-superheat determination unit (39) increases a target degree of superheat SHs and to reduce the control gain g when the target-degree-of-superheat determination unit (39) reduces the target degree of superheat SHs.

Abstract: A seal device has a for sealing a through hole in a partition includes a first seal for providing a first abutment portion that abuts against a periphery of the through hole in an entirety thereof, and a second seal for providing a second abutment portion that is made of an elastic material for abutting against an outer peripheral surface of a component disposed in the through hole. The first seal and the second seal are connected to cover an entire periphery of the through and the component, and a support member on the second seal has an inner surface shaped in a corresponding form of the component.

Abstract: A system for detecting a mis-connected state between communication lines for a multi-type air conditioner and a method thereof. The system comprises an indoor unit pipe temperature detection unit for detecting a temperature of an indoor unit pipe, and a microprocessor for controlling an opening of an electronic expansion valve based on a temperature detected by the indoor unit pipe temperature detection unit, comparing a temperature response characteristic of the indoor unit pipe with a preset temperature response characteristic of a normal indoor unit pipe based on an opening of the electronic expansion valve, and thereby judging whether the communication lines are mis-connected to one another or not. An indoor unit from which the mis-connection has been generated is fast detected, and error information is displayed. Accordingly, the mis-connected state between the communication lines is restored, thereby preventing a damage of the system due to the mis-connection.

Abstract: A system and method for controlling the temperature of a process tool uses the vaporizable characteristic of a refrigerant that is provided in direct heat exchange relation with the process tool. Pressurized refrigerant is provided as both condensed liquid and in gaseous state. The condensed liquid is expanded to a vaporous mix, and the gaseous refrigerant is added to reach a target temperature determined by its pressure. Temperature corrections can thus be made very rapidly by gas pressure adjustments. The process tool and the operating parameters will usually require that the returning refrigerant be conditioned and processed for compatibility with the compressor and other units, so that cycling can be continuous regardless of thermal demands and changes.

Abstract: In a refrigeration cycle system, temperature sensors measure the temperatures Tin and Tout of a refrigerant at the entrance and exit of an evaporator. A control circuit performs PID calculation based on signals from the temperature sensors in order to control a degree of superheat corresponding to the difference between the temperatures Tin and Tout at the entrance and exit to an aimed value, and calculates an operation amount for the opening degree of an expansion valve. In a case where the operation amount exceeds the limit of realizable velocity of driving an actuator that actuates the expansion valve, the control circuit performs a limiter process for limiting the operation amount so as not to exceed the limit value. The control circuit drives the actuator by using the operation amount after subjected to the limiter process, thereby to stably control the opening degree of the expansion valve.

Abstract: An expansion valve having a tubular member (15) for receiving a low-pressure refrigerant (14) sent from an evaporator (13) and also having a tube member (16) inserted in the tubular member (15) and receiving a high-pressure refrigerant sent from a condenser (12). The expansion valve has a valve mechanism (17) provided in the tube member (16). An end wall (18) is formed at one end (15a) of the tubular member (15), and the end wall (18) has a low-pressure inflow hole (19) for allowing the refrigerant (14) sent from the evaporator (13) to flow into the tubular member (15) and a high-pressure outflow hole (20) for allowing the refrigerant (14) to flow out from the tube member (16) into the evaporator (13).

Abstract: A refrigeration device includes a compression mechanism, a radiator, a first expansion mechanism, a second expansion mechanism, an evaporator, a first internal heat exchanger, a branch pipe, a third expansion mechanism, and a second internal heat exchanger. The first internal heat exchanger causes heat to be exchanged between refrigerant that flows from the radiator to the inflow side of the first expansion mechanism, and refrigerant that flows from the evaporator to the compression mechanism. The branch pipe branches from a third refrigerant pipe for connecting the radiator and the second expansion mechanism, and merges with the second refrigerant pipe. A third expansion mechanism is provided to the branch pipe. The second internal heat exchanger causes heat to be exchanged between refrigerant that flows out from the first expansion mechanism, and refrigerant that flows out from the third expansion mechanism.

Abstract: The present disclosure allows for easy settling of control of capability of an refrigeration apparatus for performing a supercritical refrigeration cycle. An air conditioner (10) includes: a refrigerant circuit (20) sequentially connecting a compressor (21), an outdoor heat exchanger (23), an outdoor expansion valve (24), and an indoor heat exchanger (27), and performing a supercritical refrigeration cycle in which a high pressure is a supercritical pressure or higher; and a controller (40) for controlling a plurality of objects of control including at least the compressor (21) and the outdoor expansion valve (24). The controller (40) concurrently controls the plurality of objects of control, thereby concurrently controlling a predetermined physical value as an index of an ability of the refrigeration apparatus, and the high pressure of the refrigeration cycle.

Abstract: A refrigeration system for controlling airflow around an air-cooled heat generating device includes a variable speed compressor. The refrigeration system also includes evaporators positioned along a refrigerant line in a serial configuration with respect to each other and are positioned directly in at least one of the path of airflow supplied into the heat generating components and the path of airflow exhausted from the heat generated components. The refrigeration system further includes a controller and at least one temperature sensor. The temperature sensor is configured to transmit signals related to the detected temperature to the controller, and the controller is configured to vary the speed of the variable speed compressor based upon the signals received from the temperature sensor.

Abstract: A thermostatic expansion valve is provided comprising an inlet, an outlet, first and second flow paths through the valve, a first valve element in the first flow path between the inlet and outlet, and a movable diaphragm having a first side acted on by a first fluid pressure and a second side acted on by at least a second fluid pressure. The diaphragm is movable to permit increased flow through the first flow path when the force against the first side is greater than that against the second side, and is movable to restrict flow through the first flow path when the force against the first side is less than that against the second side. The diaphragm moves in an upward direction to cause the first valve element to close the first flow path, and may continue to move in the upward direction to cause a second flow path to open.

Abstract: After a chiller unit is started, an opening command of 10 pulses is output to an electronic expansion valve, and after a predetermined period of time (at the time of starting with unload) elapses, an opening command of 100 to 150 pulses is output to open the electronic expansion valve up to a predetermined opening degree. Thereafter, a discharge side refrigerant super-heat TdSH is monitored and a closing command of 1 pulse/sec is output to the electronic expansion valve to drive the same in a closing direction in a short time until TdSH becomes 20 K. After TdSH has reached 20 K, a closing command of 1 pulse/3 sec is output to the electronic expansion valve, until TdSH becomes 25 K, to drive the electronic expansion valve 3 at a smaller speed in the closing direction than that speed in the closing direction until TdSH becomes 20 K.

Abstract: A method and a device for detecting flash gas in a vapor-compression refrigeration or heat pump system comprising a compressor, a condenser, an expansion device, and an evaporator interconnected by conduits providing a flow path for a refrigerant, by determining a first rate of heat flow of a heat exchange fluid flow across a heat exchanger of the system and a second rate of heat flow of the refrigerant across the heat exchanger, and using the rates of heat flow for establishing an energy balance from which a parameter for monitoring the refrigerant flow is derived, to thereby provide early detection of flash gas with a minimum number of false alarms.

Abstract: An electrically controlled expansion valve package (10) comprises an expansion valve (30), sensors (32, 33, 36) and control electronics (35) all included in a monolithic package that greatly simplifies installation, while also enabling performance enhancements. The expansion valve is controlled by control electronics that, among other things, determines from pressure and temperature sensors the type or nature of the refrigerant being used in the refrigeration system for adapting control of the expansion valve to the refrigerant.

Abstract: A vapor compression refrigeration system including components capable of determining the superheat at a compressor inlet is provided. The vapor compression refrigeration system may include sensors capable of making measurements from which the superheat at the compressor inlet may be determined. The vapor compression refrigeration system may be operable to compare the determined superheat level at the inlet to the compressor to a desired superheat level and generate a new evaporator discharge superheat level target for one or more evaporators operatively interconnected to the compressor to affect the superheat at the compressor inlet. The vapor compression refrigeration system may be operable to broadcast the new evaporator discharge superheat level target to the one or more evaporators over a communications bus. The vapor compression refrigeration system may update and broadcast the evaporator discharge superheat level target at programmed intervals.

Abstract: A control apparatus and associated method for a refrigeration system are provided. The control apparatus includes sensors capable of detecting controlled refrigerator zone temperatures and superheat levels of refrigerant vapour exiting an evaporator. The control module receives input from the sensors, compares the input to a determined controlled refrigerator zone set point and a learned superheat level, and generates an output with respect thereto. In particular the output modulates an electronic evaporator pressure regulating (EEPR) valve between an open and a closed position in response to detecting abnormal operation of the thermostatic expansion valve or electronic expansion valve.

Abstract: A refrigeration apparatus (10) includes: a refrigerant circuit (20) provided with a variable-opening expansion valve (13); and a valve control means (33) for controlling the opening of the expansion valve (13) by outputting to the expansion valve (13) an opening command value equal to or larger than a lower limit command value. During operation of a refrigeration cycle and in a lower-limit-controlled state in which the opening command value is equal to the lower limit command value, the valve control means (33) performs a first determination operation of determining whether the refrigerant flow through the expansion valve (13) is in an excessively large amount state or not based on a condition of refrigerant between the expansion valve (13) and the suction side of a compressor (11), and corrects the lower limit command value to a smaller value if the determination result in the first determination operation is that the refrigerant flow through the expansion valve (13) is in an excessively large amount state.

Abstract: A temperature-type expansion valve 1 includes a valve housing 110 having a first passage 121 into which a high pressure refrigerant flows, a second passage 122 through which a low pressure refrigerant flowing to an evaporator 5 flows, and a throttle passage 125 communicating the first passage 121 with the second passage 122; a valve body 130 having a valve member 131 varying a sectional area of the throttle passage 125; and an operation rod 135 for driving the valve body 130 in the interlocking arrangement with a displacement member 160 undergoing displacement in accordance with a pressure difference between a saturation pressure corresponding to an outlet temperature of the refrigerant of the evaporator 5 and an evaporation pressure of the evaporator; wherein a slide hole 124 communicating with the throttle passage 125 and accommodating the valve body 130 is formed in the valve housing 110; and the valve member 131 moves inside the slide hole 124 in the interlocking arrangement with the operation rod 135 to

Abstract: Provided is an air conditioner, particularly, an apparatus and method for controlling a super-heating degree in a heat pump system for preventing a liquid refrigerant from flowing into a compressor. The method includes: operating the heat pump system; receiving a present outdoor temperature, a pipe absorption temperature and a low pressure value of a compressor, respectively; computing a present absorption super-heating degree from a difference between the absorption temperature of the compressor and a saturated temperature at a low pressure side; and comparing an targeted absorption super-heating degree set in advance, with the computed present absorption super-heating degree according to the received outdoor temperature, and controlling the system so that the present absorption super-heating degree may follow the targeted absorption super-heating degree.

Abstract: A heat-pump hot water supply apparatus, for dissolving problems of delaying in heating rise-up time when re-starting, and ill influences upon starting characteristics, due to liquid refrigerant residing in an evaporator when the operation is stepped, within a heat-pump circuit thereof, comprises a heat-pump refrigerant circuit, in which a compressor, a water/refrigerant heat exchanger, a refrigerant adjusting valve, and an evaporator, in series, through refrigerant pipes, a direct hot-water supply circuit, into which is supplied hot water heated, obtained by heating water supplied from an outside via a water pipe by means the water/refrigerant heat exchanger, and a compressor operation controller means for stopping the compressor and also closing the refrigerant adjusting valve when the compressor stops the operation thereof, and for re-starting the compressor after opening the refrigerant adjusting valve when the compressor starts the operation, again, wherein the refrigerant within the evaporator is collect

Abstract: In a refrigerant cycle system, a compression mechanism of an electric compressor sucks and compresses refrigerant, and an electric motor that drives the compression mechanism is cooled by the refrigerant. A variable throttle mechanism decompresses the refrigerant discharged from the electric compressor. A motor temperature detector detects a temperature of the electric motor. A motor protection determiner determines whether the temperature of the electric motor detected by the motor temperature detector is equal to or higher than a criterion value. A motor protection controller controls the variable throttle mechanism so that an opening degree of the variable throttle mechanism does not decrease when the motor protection determiner determines that the temperature of the electric motor is equal to or higher than the criterion value.

Abstract: To provide a temperature sensing tube for an expansion valve in which a hunting can be prevented by slowing of a temperature reaction rate of an expansion valve, a ceramic sintered member serving as a heat transfer delay member (3) in a temperature sensing tube (1) is fixed so as not to directly contact with a tubular member (2) by fixing springs (4, 4) provided at both end portions (13, 13), whereby a heat transfer from the tubular member (2) to the ceramic sintered member becomes slow, temperature is not transferred from a mated piping directly via the tubular member, whichever outer surface of the temperature sensing tube 1 contacts with the piping, and a reaction rate with respect to a temperature rise of the expansion valve can be made slow.

Abstract: An air conditioning system is able to decrease the amount of refrigerant between a first expansion device and an injection valve and thus adjust the pressure of an injected refrigerant by decreasing the opening degree of the first expansion device and maintaining the opening degree of a second expansion device upon opening of the injection valve, thereby making the system stable upon opening of the injection valve. Furthermore, upon starting up a compressor, the opening degrees of the first and second expansion devices are partly decreased based on the start-up of the compressor and then gradually opened again, and upon completion of the start-up of the compressor, the opening amounts of the first and second expansion devices and the injection valve are controlled, thereby making the cycle more stable.

Abstract: If the degree of opening of an electronic expansion valve (14) is kept below a specified degree of opening or if the degree of superheat of refrigerant at an evaporator (15) side is kept above a specified degree of superheat, the amount of circulating refrigerant is judged to be insufficient. Thus, the volume of an air delivered by an evaporator fan (22) is reduced.

Abstract: A refrigerating air-conditioning apparatus, at least provided with no possibility that a foreign material returns to a compressor from an accumulator at a time of the pipeline-cleaning operation firstly, and provided with a possibility to perform a collecting operation for the foreign material in a short time secondary, is provided. The heat-source side unit includes an accumulator provided with a function to separate and collect the foreign material in an existing pipeline, a collecting container for collecting the foreign material separated by the accumulator, and an oil return pipeline for returning refrigerating machine oil to the compressor via a flow amount adjusting device, installed at a lower portion of the accumulator, and at a time of ordinary cooling or heating operation, the refrigerating machine oil is caused to flow into the oil return pipeline, and at a time of pipeline cleaning and foreign material-collecting operations, the flow amount adjusting device is fully closed.

Abstract: A refrigeration device includes a control device and a multiple cooling elements. A supply header delivers refrigerant to the cooling elements and a return header returns refrigerant from the cooling elements. A single pressure sensor provides a signal representative of a pressure of the refrigerant in the return header to the control device, and a single temperature sensor provides a signal representative of a temperature of the refrigerant in the return header to the control device. The control device provides an output signal to control each of the cooling elements, in response to the signals from the single temperature sensor and the single pressure sensor.

Abstract: An ejector cycle system with a refrigerant cycle through which refrigerant flows includes an ejector disposed downstream of a radiator, a first evaporator located to evaporate refrigerant flowing out of the ejector, a branch passage branched from a branch portion between the radiator and a nozzle portion of the ejector and coupled to a refrigerant suction port of the ejector, a throttling unit located in the branch passage, and a second evaporator located downstream of the throttling unit to evaporate refrigerant. In the ejector cycle system, a variable throttling device is located in a refrigerant passage between a refrigerant outlet of the radiator and the branch portion to decompress the refrigerant flowing out of the radiator.

Abstract: A system and method for monitoring an overheat condition of a compressor is provided. A compressor connected to an evaporator. A suction sensor outputs a suction signal corresponding to a temperature of refrigerant entering the compressor. A control module is connected to the evaporator sensor and the suction sensor and determines an evaporator temperature, calculates a suction superheat temperature based on the evaporator temperature and the suction signal, and monitors an overheat condition of the compressor by comparing the suction superheat with a predetermined suction superheat threshold.

Abstract: A system and method for a compressor may include an inverter drive connected to the compressor that receives electric power and modulates a speed of the compressor by modulating a frequency of the electric power. A control module connected to the inverter drive monitors compressor power data and compressor speed data from the inverter drive, and calculates a saturated condenser temperature of a refrigeration system associated with the compressor based on the compressor power data and the compressor speed data.

Abstract: A humidity control system (10) includes a refrigerant circuit (50) including a compressor (53), a first adsorption heat exchanger (51) carrying an adsorbent thereon, an expansion valve (55) adjustable in opening and a second adsorption heat exchanger (52) carrying an adsorbent thereon, supplies humidity-controlled air to a room by operating alternately in a first batch mode in which the second adsorption heat exchanger (52) adsorbs moisture in air and the first adsorption heat exchanger (51) releases moisture to air and a second batch mode in which the first adsorption heat exchanger (51) adsorbs moisture in air and the second adsorption heat exchanger (52) releases moisture to air, and controls the opening of the expansion valve (55), when a valve control start time has come a predetermined time after the start of each batch mode, so that the degree of superheat of refrigerant in the refrigerant circuit (50) reaches a predetermined value.

Abstract: Disclosed herein is a method of controlling a linear expansion valve of a cooling cycle apparatus. The method comprises a first step of calculating a target opening level value according to suction overheat level of compressors to control a linear expansion valve based on the calculated target opening level value, and a second step of calculating a new target opening level value according to the suction overheat level of the compressors and discharge temperature of the compressors to control the linear expansion valve based on the calculated new target opening level value. Consequently, the discharge temperature of the compressors is prevented from being excessively increased, and therefore, the compressors are prevented from being overheated and damaged, and reliability of the cooling cycle apparatus is improved.

Abstract: A sufficient heating capacity can be displayed even in cold districts with atmospheric temperatures of ?10° C. or less by improving the heating capacity in the refrigerant air conditioner much more than that of conventional gas injection cycles.

Abstract: A bypass factor of an evaporator is used to indicate when an air filter of an HVAC is clogged. The bypass factor represents the amount of air that is bypassed without direct contact with the evaporator. As the air filter clogs, the bypass factor decreases. The bypass factor can also be used for early detection of clogging of the air filter. A first bypass factor is calculated by using the temperature measurements, and a second bypass factor is calculated by using the airflow rate of the air. The difference between the two bypass factors determines the error. An increase in the error indicates that the air filter is clogged. A coefficient of performance of the evaporator can also be calculated to detect if the air filter is clogged. A decrease in the coefficient of performance indicates that the air filter is clogged.

Abstract: A vapor compression air conditioning system includes a motor operated expansion valve and control unit including sensors for determining the amount of superheat of the working fluid at or adjacent to the compressor inlet. Expansion valve position is adjusted to maintain a predetermined amount of superheat. The sensors may sense working fluid evaporator temperature and temperature downstream of the evaporator. Dual motor operated expansion valves may be disposed in the working fluid conduit between the heat exchangers in a reversible system. In operation, the expansion valve position may be set as a function of ambient temperature, a previous position, and predetermined superheat requirements to minimize liquid ingestion by the compressor.

Abstract: An air conditioning apparatus includes a refrigerant circuit and an operation control section. The operation control section is capable of performing a refrigeration cycle for causing an outdoor heat exchanger to function as a refrigerant condenser and an indoor heat exchanger to function as a refrigerant evaporator, while performing superheat degree control for controlling the aperture of an indoor expansion valve so that the degree of superheat of the refrigerant at the outlet from the indoor heat exchanger is constant. The operation control section sets a lower aperture limit for the indoor expansion valve to perform the superheat degree control, and reduces the lower aperture limit when the refrigerant at the outlet from the indoor heat exchanger is detected to be wet.

Abstract: In a refrigerating air conditioning system using refrigerant such as CO2 used in a supercritical area, a highly efficient refrigerating air conditioning system is provided by adjusting the amount of refrigerant in a radiator which contributes to the efficiency of the system stably and quickly. During heat utilizing operation, the superheat at the exit of an evaporator is controlled to a predetermined value by controlling the opening of an expansion valve provided on the upstream side of the evaporator, and an expansion valve is controlled so that the state of refrigerant in a connection pipe on the high-pressure side becomes a supercritical state. In this state, a flow rate control valve is controlled to change the density of the refrigerant stored in a refrigerant storage container and the amount of refrigerant existing in the radiator is adjusted.

Abstract: A refrigerant system has at least one unloader valve selectively communicating refrigerant between the compressor compression chambers and a point upstream of the evaporator. When the compressor is run in unloaded mode, partially compressed refrigerant is returned to a point upstream of the evaporator. In an unloaded mode, a higher refrigerant mass flow rate passes through the evaporator, as compared to prior art where the by-passed refrigerant was returned downstream of the evaporator. This increases system efficiency by more effectively returning oil which otherwise might be left in the evaporator back to the compressor. Also, the amount of refrigerant superheat entering the compressor in unloaded operation is reduced as compared to the prior art compressor systems, wherein the by-passed refrigerant is returned directly to the compressor suction line. Reduced refrigerant superheat increases system efficiency, improves motor performance and reduces compressor discharge temperature.

Abstract: Combined medium and low temperature refrigeration circuit for circulating a refrigerant in a predetermined flow direction includes, in flow direction, a heat-rejecting heat exchanger, a medium temperature refrigeration consumer, a medium pressure vapor separator having a vapor portion and a liquid portion connected to the medium temperature refrigeration consumer unit, a low temperature refrigeration consumer connected to the liquid portion of the medium pressure vapor separator, and a compressor unit having an inlet connected to the vapor portion of the medium pressure vapor separators and the low temperature refrigeration consumer.

Abstract: An expansion valve includes a valve body 1. The valve body 1 includes a first throttle 5 and a second throttle 6 arranged downstream from the first throttle 5. The second throttle 6 includes an outer surface of the second valve portion 16 and an inner surface of the second valve hole 13. A helical groove or a linear groove is formed in the outer surface of the second valve portion 16 or the inner surface of the second valve hole 13. Further, at least either one of the outer surface of the second valve portion 16 and the inner surface of the second valve hole 13 is tapered toward a distal end of a valve member 4.

Abstract: The present invention relates to an air conditioning device, in particular for motor vehicle, including an air-conditioning circuit comprising a compressor (14), a condenser (11), and/or an internal exchanger, an electric expansion valve (12) which opening ratio is changed according to a control signal, and an evaporator (13), which are traversed in this order by a refrigerant fluid. The installation comprises in addition a control unit (40) suitable to manage the control signal of the expansion valve so as to control a parameter of the evaporator (13) over heating or the condenser (11) sub cooling in accordance with a predetermined regulation law. The control signal of the compressor valve is such as: Electric architecture is optimal while using a minimum of sensors The optimal coefficient of performance is maximum The control of the cold power A protection is ensured to limit the discharge temperature of the compressor and/or the aspiration temperature of the compressor.

Abstract: A control procedure operates an expansion valve of an air conditioning system. The control procedure utilizes a first control procedure to bring a calculated superheat value within a range of a target superheat value, and a second control procedure to cause the calculated superheat value to match the target superheat value. Both the first and second control procedures preferably use Proportional, Integral, Derivative control algorithms.

Abstract: A control system for a cooling system includes a first sensor for sensing a property indicative of demand for cooling and a controller coupled to the sensor. The controller produces the variable duty cycle control signal in response to the property and causes the compressor and valve to vary a cooling capacity of the cooling system in response to the variable duty cycle control signal. The sensor may sense the pressure, temperature, or both. The valve may be a suction-side pressure regulator or a liquid-side expansion valve of the solenoid or stepper type.

Abstract: A refrigeration system to increase the subcooling degree of refrigerant flowing through a main refrigerant circuit is provided. The refrigeration system is configured such that a portion of the refrigerant flowing through the main refrigerant circuit can be made to bypass the remainder of the main refrigerant circuit in a bypass refrigerant circuit so as to be returned to the intake side of a compressor and to be used to cool the refrigerant flowing through the main refrigerant circuit to a subcooled state.

Abstract: A system for monitoring a fluid in an environmental control system includes a mechanical resonator positioned for contacting a thermal change fluid. In some embodiments, the mechanical resonator is positioned in a passage for containing the thermal change fluid. Suitable thermal change fluids include an R-134A refrigerant, a mineral oil, an ester lubricant or a mixture thereof; a superheated refrigerant; or an elevated pressure and elevated temperature vapor, an elevated pressure liquid, a reduced pressure liquid, a reduced pressure vapor and combinations thereof. The mechanical resonator can be a flexural resonator or a torsion resonator. In some embodiments, the mechanical resonator is a tuning fork resonator. Methods of the invention include monitoring a response of the mechanical resonator to the thermal change fluid. In some embodiments, at least a portion of the mechanical resonator is translated through the thermal change fluid and the response of the resonator to the fluid is monitored.

Abstract: A new feedback linearization approach to advanced control of single-unit and multi-unit HVAC systems is described. In accordance with the approach of the invention, this new nonlinear control includes a model-based feedback linearization part to compensate for the nonlinearity in the system dynamics. Therefore, the evaporating temperature and superheat values can be controlled by linear PI control designs to achieve desired system performance and reliability. The main advantages of the new nonlinear control approach include (1) better performance even with large model errors, (2) being able to adapt to indoor unit turn on/off operation, (3) much smaller PI control gains compared to that of current feedback PI controls, (4) much easier design procedures since there is no need for tuning the PI control gains over wide range operation.

Abstract: An expansion valve control system, a method of controlling an expansion valve and a refrigeration unit incorporating the same. In one embodiment, the expansion valve control system includes (1) a superheat error circuit configured to derive a superheat error for a fluid associated with the expansion valve and (2) a valve position circuit, associated with the superheat error circuit, configured to reposition the expansion valve proportionally based on both a current position thereof and the superheat error.

Abstract: A defrost system for a temperature controlled storage unit includes an enclosure providing a space for storage of products. A refrigeration system has a supply line and a return line coupled to a cooling element to circulate a refrigerant through the cooling element to provide cooling to the space. A control module initiates a plurality of defrost modes on a predetermined frequency and for a predetermined duration by reducing a flow rate of the refrigerant through the cooling element so that a superheat temperature of the refrigerant in the cooling coil is increased to a predetermined range.