Showing papers on "Thermal expansion valve published in 2009"

Method and apparatus for cooling

Abstract: A method of calculating net sensible cooling capacity of a cooling unit (10) includes measuring a discharge pressure from of fluid from a compressor (30) and a suction pressure from an evaporator (44), calculating a condensing temperature of fluid flowing from the compressor and an evaporating temperature of fluid flowing from the evaporator, calculating a mass flow rate of fluid flowing from the compressor, calculating enthalpy of fluid flowing from the compressor, of fluid flowing from the thermal expansion valve (48), and of fluid flowing from the evaporator, calculating a mass flow rate of fluid flowing through the hot gas bypass valve (64), and calculating net sensible cooling capacity. Embodiments of cooling units and other methods are further disclosed.

Performance improvement of the vapour compression refrigeration cycle by a two‐phase constant area ejector

Abstract: The performance of a vapour compression system that uses an ejector as an expansion device was investigated. In the analysis, a two-phase constant area ejector flow model was used. R134a was selected as the refrigerant. According to the obtained results, for any operating temperature there are different optimum values of pressure drop in the suction chamber, ejector area ratio, ejector outlet pressure and cooling coefficient of performance (COP). As the difference between condenser and evaporator temperatures increases, the improvement ratio in COP rises whereas ejector area ratio drops. The minimum COP improvement ratio in the investigated field was 10.1%, while its maximum was 22.34%. Even in the case of an off-design operation, the performance of a system with ejector is higher than that of the basic system. Copyright © 2008 John Wiley & Sons, Ltd.

A model-driven multivariable controller for vapor compression refrigeration systems

Abstract: A model-driven controller for vapor compression refrigeration systems is presented herein. Mathematical sub-models were developed for each of the system components: heat exchangers (condenser and evaporator), variable-speed compressor and variable-orifice electric expansion device. The overall system simulation model was used to design a MIMO controller based on the linear-quadratic Gaussian method using a state observer of the Kalman filter type. A purpose-built testing apparatus comprised of a variable-speed compressor and a pulse-width modulated expansion valve was used to collect data for the system identification and model validation exercises. It was found that the model reproduces the experimental trends of the working pressures in conditions far from the operation point (±30%) with a maximum deviation of ±5%. Additional experiments were also performed to verify the ability of the controller of tracking reference changes and rejecting thermal load disturbances as high as 15%.

Exergy analysis of multistage cascade low temperature refrigeration systems used in olefin plants

Abstract: This paper provides an exergy analysis for multistage cascade low temperature refrigeration systems used in olefin plants. The equations of exergy destruction and exergetic efficiency for the main system components such as heat exchangers, compressors and expansion valves are developed. The relations for total exergy destruction in the system and the system overall exergetic efficiency are obtained. Also, an expression for minimum work requirement for the refrigeration systems of olefin plants is developed. It shows that the minimum work depends only on the properties of incoming and outgoing process streams cooled or heated with refrigeration system and the ambient temperature. Using actual work input values, the exergetic efficiency of the low temperature cascade refrigeration system of a typical olefin plant is determined to be 30.88% indicating a great potential for improvements. The novelty of this paper includes the suggestions for increasing efficiencies, along with discussion about the reasons for deviation from reversible processes.

Modelling refrigerant distribution in microchannel evaporators

Abstract: The effects of refrigerant maldistribution in parallel evaporator channels on the heat exchanger performance are investigated numerically. For this purpose a 1D steady state model of refrigerant R134a evaporating in a microchannel tube is built and validated against other evaporator models. A study of the refrigerant distribution is carried out for two channels in parallel and for two different cases. In the first case maldistribution of the inlet quality into the channels is considered, and in the second case a non-uniform airflow on the secondary side is considered. In both cases the total mixed superheat out of the evaporator is kept constant. It is shown that the cooling capacity of the evaporator is reduced significantly, both in the case of unevenly distributed inlet quality and for the case of non-uniform airflow on the outside of the channels.

A transcritical CO2 heat pump for simultaneous water cooling and heating: Test results and model validation

Abstract: Working prototype of a transcritical CO2 heat pump system for simultaneous cooling and heating of water is designed and developed based on numerical simulation studies. System behaviour and performance of the system have been studied experimentally for various operating parameters such as system pressure, water mass flow rate, water inlet temperature and expansion valve opening. Finally, the system simulation model predictions have been validated by the test data. Test results show the effect of water mass flow rate to be modest for both evaporator and gas cooler, whereas the effect of water temperature at the inlet to the gas cooler on system performance is significant. The expansion valve opening has a significant effect as well near the full valve closing condition (up to 20°). Validation of the simulation model shows reasonably good agreement (a maximum deviation of 15%) with the test data exhibiting fairly similar trends. Copyright © 2008 John Wiley & Sons, Ltd.

Freezer-refrigerator and cooling storage unit

Abstract: A freezer-refrigerator comprising: a refrigeration compartment (2) for refrigerating and storing an object to be stored; a freezing compartment (4) for freezing and storing an object to be stored; a first compressor (11) for operating a first refrigeration cycle (10) in which a first refrigerant flows; a first heat dissipater (12) provided to a high-temperature section of the first refrigeration cycle (10); a first evaporator (14) provided to a low-temperature section of the first refrigeration cycle (10); a second compressor (21) for operating a second refrigeration cycle (20) in which a second refrigerant flows; a second evaporator (24) provided to a low-temperature section of the second refrigeration cycle (20); and an intermediate heat exchanger (31) for performing heat exchange between the low-temperature section of the first refrigeration cycle (10) and a high-temperature section of the second refrigeration cycle (20). The first evaporator (14) cools the refrigeration compartment (2), and the second evaporator (24) cools the freezing compartment (4).

Cooling system for a battery system and a method for cooling the battery system

Abstract: A cooling system for a battery system and a method for cooling the battery system are provided. The cooling system includes a housing having first and second enclosed portions, and a first evaporator and a first evaporator fan disposed in the first enclosed portion that recirculates air in a first closed flow path loop within the first enclosed portion. The first evaporator extracts heat energy from the air in the first closed flow path loop to reduce a temperature level of a first battery module in the first enclosed portion. The cooling system further includes a condenser disposed in the second enclosed portion and fluidly coupled to the first evaporator, which receives heat energy in a refrigerant from the first evaporator and dissipates the heat energy. The cooling system further includes a compressor disposed in the second enclosed portion that recirculates the refrigerant through the first evaporator and the condenser.

Evaporator For Loop Heat Pipe System

Abstract: Provided is an evaporator for a loop heat pipe system including a condenser, a vapor transport line, and a liquid transport line, and more particularly, to an evaporator having an increased contact area between a sintered wick and a heating plate.

Transcritical fluid cooling for aerospace applications

Abstract: A cooling system (16) includes a compressor (36) for compressing a refrigerant from a subcritical state to a supercritical state, a cooler (38) for transferring heat from the refrigerant, an expander (40) for expanding the refrigerant in the supercritical state, an expansion valve (42) for expanding the refrigerant from the supercritical state to the subcritical state and an evaporator (44) for transferring heat from a cooling fluid to the refrigerant in the subcritical state. Work extracted by the expander provides power to the compressor. A method (70) for cooling a vehicle includes compressing a refrigerant from a subcritical state to a supercritical state (72), cooling the refrigerant (74), expanding the refrigerant in the supercritical state (76) where work produced by expanding the refrigerant is used to compress the refrigerant, expanding the refrigerant from the supercritical state to the subcritical state (78), cooling a cooling fluid with the refrigerant in the subcritical state (80) and cooling vehicle components with the cooling fluid.

Investigation of the Startup Condition of a Closed-Loop Oscillating Heat Pipe

Abstract: This article develops a concept for a suitable startup condition for a closed-loop oscillating heat pipe (CLOHP). This concept was developed by using visual data and the thermodynamics theory for predicting the amount of vapor evaporation and condensation in a CLOHP. The visual data indicated that the key to a suitable startup is the amount of net vapor expansion in the evaporator and the amount of net collapsed vapor in the condenser. Initial dryout, an event that occurs after a startup failure, results when the net vapor expansion is higher than the amount of net vapor collapsed. This situation obstructs the replacement process. This is a mechanism in which the volume of mixture from the condenser section flows to the evaporator section to replace the volume of mixture that leaves the evaporator section. When the replacement process is impeded, all of the liquid in the evaporator section evaporates and the evaporator section is not refilled by the mixture from the condenser section. The evaporator secti...

Decoupling features for diagnosis of reversing and check valve faults in heat pumps

Abstract: Recently, a decoupling-based (DB) fault detection and diagnosis (FDD) method was developed for diagnosing multiple-simultaneous faults in air conditioners (AC) and was shown to have very good performance. The method relies on identifying diagnostic features that are decoupled (i.e., insensitive) to other faults and operating conditions. The current paper extends the DB FDD methodology to heat pumps. Heat pumps have all the same faults as occur for air conditioners with additional faults associated with components that accommodate heating mode, including reversing valve leakage and check valve leakage. Decoupling features were developed for these additional faults and laboratory evaluations were performed to evaluate diagnostic performance. It was found that check valve leakage could be detected and diagnosed before the heating capacity degradation reached 5% for a system with a fixed orifice expansion (FXO) device and 3% for the same system retrofit with a thermal expansion valve (TXV). Furthermore, the feature for check valve leakage is very insensitive to other faults and operating conditions. The decoupling feature for reversing valve leakage could successfully detect and diagnose faults for a TXV system before the heating capacity degraded 6% and was also insensitive to other faults and operating conditions. However, this feature did not work well for a system with an FXO in heating mode because the refrigerant exiting the evaporator and entering the reversing valve was typically a two-phase mixture. Fortunately, it was possible to diagnose this particular fault at many operating conditions in cooling mode for the system with an FXO.

Evaporator Phase Change Thermal Siphon

Abstract: An air conditioning system including an evaporator having a manifold and a plurality of tubes extending downward in a vertical direction from the manifold. The evaporator defines at least one PCM tank engaging the manifold for storing a phase change material. When operating in a first operating mode, heat is transferred from the phase change material to the refrigerant to freeze and cool the phase change material. When operating in a second operating mode, heat is transferred from the refrigerant to the frozen phase change material to condense the refrigerant. The condensed refrigerant falls downwardly through the tubes and receives heat from a flow of air to cool the air and evaporate the refrigerant. The evaporated refrigerant rises upwardly back to the low pressure of the cold manifold.

Frosting dehumidifier with enhanced defrost

Abstract: A dehumidifier apparatus comprises a housing having an air inlet for receiving incoming air, an air outlet spaced therefrom for allowing the air to exit from the housing, the housing being configured to provide an interior air passageway connecting the air inlet to the air outlet; an air mover mounted within the air passageway for moving the air through the air passageway from the air inlet to the air outlet; a compressor mounted in the housing for compressing a refrigerant; an evaporator located within the air passageway for evaporating the refrigerant during a dehumidifying cycle, and thereby cooling air flowing through the evaporator and causing water in the air to condense on a surface of the evaporator; a condenser for condensing the refrigerant during the dehumidifier cycle, the condenser being located in the air passageway downstream of the evaporator in series with the evaporator; refrigerant flow lines configured to allow for a flow of the refrigerant between the compressor, the condenser, and the evaporator; and a defrosting cycle system for performing a defrosting cycle during a frosting condition of the evaporator, wherein during the defrosting cycle the flow of the refrigerant is reversed, causing the evaporator to condense the refrigerant and the condenser to evaporate the refrigerant. The compressor and the air mover are configured to run continuously during the dehumidifying cycle and the defrosting cycle.

System and device comprising a combined condenser and evaporator

Abstract: The invention relates to a system and a device for cooling and/or warming which comprises at least a refrigerant circuit (2) with at least a compressor (3), a condenser (4), an evaporator (7) and an expansion means (6). The invention is effected by the evaporator and the condenser being combined/integrated in a single common unit (16) which comprises an internal heat exchanger (19).

Automotive climate system and method of controlling same

Abstract: An automotive climate control system includes an evaporator, a variable speed compressor and a controller. The controller is configured to periodically alter a previous target evaporator temperature at a selected rate to generate a current target evaporator temperature, select a target compressor speed based on a difference between an actual evaporator temperature and the current target evaporator temperature, and command the compressor to operate at the target compressor speed.

Heat pump type hot water supply outdoor apparatus

Abstract: A heat pump type hot water supply outdoor apparatus, wherein a compressor (3), a water heat exchanger (2), a first expansion valve (6), a medium pressure receiver (5), a second expansion valve (7), and an air heat exchanger (1) are connected circularly, has an injection circuit (13), which is a bypass for a part of the refrigerant between the medium pressure receiver and the second pressure reduction unit, to inject the part of refrigerant into a compression chamber of the compressor, and has a third expansion valve (8) and an internal heat exchanger (9) for carrying out heat exchange between the refrigerant whose pressure is reduced by the third expansion valve and the refrigerant between the medium pressure receiver and the second expansion valve, a pressure detection sensor (12) for detecting a condensing pressure, and a controller (14) for starting an injection control by the third expansion valve at the time when the condensing pressure detected by the pressure sensor or the condensing temperature calculated from the condensing pressure becomes a first predetermined value or more and stopping the injection control at the time when the condensing pressure or the condensing temperature becomes a second predetermined value which is smaller than the first predetermined value, or less. With this arrangement, an appropriate injection control can be realized and a high hot water supply/heating capability operation can be carried out.

Capacity modulation compressor and air conditioning system having the same

Abstract: Provided is an air conditioning system comprised of a plurality of indoor units connected to each other in parallel, each having an expansion valve, and an outdoor unit including a plurality of compressors, in which at least one of the compressors provided to the outdoor unit is a capacity modulation compressor including an electromotive driving unit for driving a plurality of compression units capable of selectively compressing a working fluid, and the electromotive driving unit for the capacity modulation compressor has a stator with a coil wound around thereon and a rotor rotating inside the stator, the rotor being an LSPRM including a rotor core, flux barriers, permanent magnets and conductive bars.

Heat pump hot water supply system

Abstract: In a heat pump water heating system (1) including a refrigerant circuit (30) having a compressor (11a), a four-way valve (11b), a water heat exchanger (11c), an expansion valve (11d), and a heat source end heat exchanger (20a) being piping-connected in series, and a hot water storage tank (13) connected to a water circuit (12) of the water heat exchanger (11c) for supply and storage of hot water generated at the water heat exchanger (11c), at least the compressor (11a), the four-way valve (11b), and the water heat exchanger (11c) constituting the refrigerant circuit (30), and the hot water storage tank with water circuitry connected to the water heat exchanger (11c) are accommodated together in a single casing to constitute a main unit (10), and the heat source end heat exchanger (20a) is configured to separate from the main unit (10) by a piping connection

Air conditioner and refrigerant amount determining method

Abstract: An air conditioning apparatus and a refrigerant quantity determination method are provided, whereby a refrigerant quantity can be determined in a simple and accurate manner without compromising the reliability of a compressor. A refrigerant circuit (10) has a compressor (21), an outdoor heat exchanger (23) that functions as a condenser, an indoor expansion valve (41, 51), an indoor heat exchanger (42, 52) that functions as an evaporator, an indoor unit interconnection pipe (4b, 5b), a liquid refrigerant connection pipe (6), a gas refrigerant connection pipe (7), and an outdoor unit interconnection pipe (8). A controller (9) performs liquefaction control for liquefying refrigerant and placing the refrigerant in a portion extending from the indoor expansion valve (41, 51) to the outdoor heat exchanger (23). The controller (9) directly or indirectly regulates the flow rate of refrigerant flowing through a liquid bypass circuit (70) from a liquid reserving portion (Q) toward the gas refrigerant connection pipe (7). A liquid level detection sensor (39) detects at least one of either a volume of liquid refrigerant in the portion where liquid refrigerant accumulates and a physical quantity equivalent to the volume.

Evaporator apparatus and method for modulating cooling

Abstract: This invention relates to a method and an apparatus for a modulating air conditioning system having increased energy efficiency and greater turndown capabilities. A modulating air conditioning system includes modulating at least one of the following components: a compressor, a compressor driver, a condenser fan, an evaporator fan, an effective evaporator surface area, an effective condenser surface area and/or an expansion device.

Air conditioning system used for removable emergency escape capsule for coal mine

Abstract: The invention belongs to the fields of safety equipment and air conditioner refrigeration, which relate to an air conditioning system of a movable emergent rescue capsule for a coal mine. The air conditioning system comprises an outside capsule refrigerating unit consisting of a refrigeration compressor, a finned heat exchanger, a condensing fan and an expansion valve, and an inside capsule air conditioning device consisting of an upper ice storage tank, a lower ice storage tank and an explosionproof fan. The air conditioning system has main function of conditioning the humidity and the temperature inside the rescue capsule by the least electric quantity when the coal mine has accident, and simultaneously keeping the food fresh. Under normal condition, an explosionproof ice storage unit outside the air conditioning system maintains the ice quantity of the inside capsule air conditioning device by a mine power source; and in cataclysm state, when the outside power supply is interrupted, the air conditioning system can independently work and achieve the refrigeration by fewer energy sources, is not influenced by power reserve in the capsule and the outside environment temperature, provides necessary cold quantity for the rescue capsule, and simultaneously reduces the temperature in the capsule through the condensation. The air conditioning system has simple, convenient and quick temperature regulating control operation and maintenance, and is suitable for maintaining the temperature and the humidity of the rescue capsule under the condition that the supply of the outside energy source is interrupted.

Air conditioning system and accumulator thereof

Abstract: An air conditioning system having an outdoor heat exchanger and an indoor heat exchanger between which a refrigerant circulates to effect a heat exchange between the refrigerant and outdoor air at the outdoor heat-exchanger and to effect another heat exchange between the refrigerant and indoor air at the indoor heat exchanger, the air conditioning system which includes a compressor sucking the refrigerant to compress and discharging the resulting refrigerant, a liquid pump sucking the refrigerant to discharge, an expansion valve expanding the refrigerant, and an accumulator serving for gas-liquid separation of the refrigerant and accumulating the refrigerant in liquid phase, wherein when the compressor is brought into operation for indoor air cooling, the compressor, the outdoor heat exchanger, the expansion valve, the indoor heat exchanger, and the accumulator are connected in such an order to circulate the refrigerant therethrough, wherein suction lines of the respective compressor and liquid pump are in parallel to suck the refrigerant from the accumulator, and wherein when the compressor and the liquid pump are concurrently operated for indoor air cooling, a discharge line of the liquid pump is connected to the outdoor heat exchanger for discharging the refrigerant therefrom.

Fresh food ice maker control

Abstract: A refrigeration system is provided with an ice maker chamber within a fresh food compartment. The refrigeration system includes a refrigeration path and an ice maker path. The ice maker path includes an electronic expansion valve for controlling the refrigerant entering an ice maker evaporator and an evaporator pressure regulator. Controlling the refrigeration system includes the steps of sensing a first refrigerant temperature at an exit of the ice maker evaporator and controlling a first control of the electronic expansion valve until the temperature reaches a temperature target. The method of controlling can further include comparing a slope of the temperature to at least one of a minimum, a target, or a maximum setting to adjust the control. Subsequently, a second control for the electronic expansion valve can be repeatedly adjusted by evaluating the first refrigerant temperature and the slope.

A simulation environment for dry-expansion evaporators with application to the design of autotuning control algorithms for electronic expansion valves

Abstract: In this paper some results of a research project aimed at deriving high-performance, adaptive control algorithms for electronic expansion valves (EEVs) to be used in finned-coiled, dry-expansion evaporators for refrigeration systems are reported. With the aim of developing a software environment that can be used for controller design, rapid prototyping, optimization of data collection and test design, virtual prototyping approach to design was adopted. The development of a distributed dynamic simulation model of the evaporator coupled with an electronic expansion valve, and its use for deriving autotuning PID control algorithms is described. Experimental results confirm the effectiveness of this kind of approach.