Showing papers on "Thermal expansion valve published in 2014"

Experimental investigation of a two-phase ejector cycle suitable for use with low-pressure refrigerants R134a and R1234yf

Abstract: This paper presents the results of an experimental investigation in which the performance of the low-pressure fluids R134a and R1234yf was compared between a two-phase ejector cycle and expansion valve cycles. An alternate two-phase ejector cycle, in which the pressure lift provided by the ejector was utilized in order to provide multiple evaporation temperatures, was constructed and tested. The experimental results show that ejectors designed for low-pressure fluids were able to achieve similar but lower work recovery efficiencies compared to CO2 ejectors. When compared to a two evaporation temperature expansion valve cycle, the ejector cycle showed maximum COP improvements of 12% with R1234yf and 8% with R134a. When compared to a single evaporation temperature expansion valve cycle, the ejector cycle showed maximum COP improvements of 6% with R1234yf and 5% with R134a. The effect of evaporator design on ejector cycle COP improvement was also demonstrated experimentally.

A CFD-based investigation of the energy performance of two-phase R744 ejectors to recover the expansion work in refrigeration systems: An irreversibility analysis

Abstract: A CFD-based numerical analysis of the flow irreversibility in R744 ejectors is presented. A validated CFD tool was used to investigate three cases that were differentiated by the mass flow rate per unit area (mass flux) that passed through the mixer, which represented three dissimilar flow patterns. The mixer mass flux was found to significantly affect the ejector performance both locally and globally. An original approach was introduced to assess the contribution of the local irreversibilities to the overall entropy increase. A new factor was proposed to evaluate the ejector performance based on the reference entropy increase in a classic expansion valve. In addition, the influence of the mixer diameter and length on the ejector performance was numerically analysed, which showed that the effects of both geometric parameters may be significant. Namely, in the conditions considered, both enlargement of the mixer cross section area by 17.4% as well as shortening the mixer length by 33.3% resulted in the increase of the overall entropy growth rate by 8.9% and 5.4%, respectively.

Theoretical energy performance evaluation of different single stage vapour compression refrigeration configurations using R1234yf and R1234ze(E) as working fluids

Abstract: R1234yf and R1234ze(E) have been proposed as alternatives for R134a in order to work with low GWP refrigerants, but this replacement results generally in a decrease of the performance. For this reason, it is interesting to explore ways to improve the system performance using these refrigerants. In this paper, a comparative study in terms of energy performance of different single stage vapour compression configurations using R1234yf and R1234ze(E) as working fluids has been carried out. The most efficient configuration is the one which uses an expander or an ejector as expansion device. On the other hand, using an internal heat exchanger in a cycle which replaces the expansion valve by an expander or an ejector could produce a detrimental effect on the COP. However, for all the configurations the introduction of an internal heat exchanger produces a significant increment on the cooling capacity.

Preliminary experimental results on the R134a refrigeration system using a two-phase ejector as an expander

Abstract: The use of an ejector as an expansion device instead of an expansion valve for expansion work recovery in a vapor-compression cycle was experimentally investigated. The coefficient of performance (COP) values for both conventional and ejector systems were experimentally investigated under the same external conditions. It was observed that, although the drop in the refrigerant pressure in the evaporator of the ejector system was almost negligible, it rose as high as 133 kPa in the conventional system. Depending on the operating conditions, it was found that the work recovery in the ejector was between 14% and 17%. It was also found that the refrigeration system with an ejector as the expander exhibited a COP that was 6.2–14.5% higher than that of the conventional system. The experimental results were found to comply with the theoretical results within an error of approximately 10%.

Experimental analysis of a new method for overfeeding multiple evaporators in refrigeration systems

Abstract: An innovative method for feeding flooded evaporators, arranged in parallel in R744 plants, is presented. In order to promote evaporators overfeeding, an ejector circulates liquid from the low pressure receiver back to the intermediate pressure receiver. Since there is not a need for superheat at the evaporator exit, each evaporator expansion valve can be controlled by a signal representative, either of the evaporator load, or the evaporator performance, such as the air temperature at its inlet or outlet. When compared to dry-expansion evaporator systems, the proposed solution offers energy saving and smooth operating conditions, typical of flooded evaporators, while still maintaining a simple plant lay-out. The concept was experimentally validated: the evaporators were maintained in flooded conditions, while the ejector was able to promote liquid recirculation. Direct comparison with dry-expansion operations was performed. The suggested method is mainly intended for commercial refrigeration plants, where many evaporators are arranged in parallel.

Refrigeration cycle system

Abstract: A condenser (2), an electronic expansion valve (5), an evaporator (6), and a motorized suction throttle valve (8) are connected in series with a compressor. When a capacity is increased, the electronic expansion valve (5) is controlled to be in a throttling direction and the motorized suction throttle valve (8) is controlled to be in an unthrottling direction in association with the control of the electronic expansion valve (5), and when a capacity is decreased, the electronic expansion valve (5) is controlled to be in an unthrottling direction and the motorized suction throttle valve (8) is controlled to be in a throttling direction in association with the control of the electronic expansion valve (5). While a capacity control of a compressor by a throttle control is been carried out, such associated control is made between the electronic expansion valve (5) and the motorized suction throttle valve (8), realizing a fine temperature control in a refrigerating machine without hunting.

Modelling thermostatic expansion valves

Abstract: This paper describes and evaluates the development of generalised steady state and transient mathematical models for thermostatic expansion valves (TEVs) of the types used in commercial refrigeration systems The model is of a generalised nature, because it is not necessary to input performance or geometrical data for a particular valve to operate the model However, if required, the models can provide an accurate correlation of valve manufacturer's data Derivations are provided and validating data is presented The mathematical models described in the paper form part of computer software that simulates the thermal operation of whole refrigeration systems The software is titled Vapour Compression Refrigeration System (VCRS) simulator, and by way of example the paper presents results from the VCRS simulator which are used to aid a discussion of operating faults, such as hunting and under damping and their possible causes, where these can be attributed to the expansion valve

High-heat-discharge-quantity refrigerating and heating temperature control system for reaction kettle

Abstract: The invention relates to a high-heat-discharge-quantity refrigerating and heating temperature control system for a reaction kettle. The high-heat-discharge-quantity refrigerating and heating temperature control system comprises a reaction kettle, wherein one end of the reaction kettle is sequentially connected with a heating pipe, an electric proportioning regulating valve, a first cold storage tank and an evaporation heat exchanger through a fourth pipeline, the output end of the evaporation heat exchanger is sequentially connected with a first circulation pump, a first one-way valve, an expansion tank and an exhaust valve through a first pipeline, the exhaust valve is connected to the other end of the reaction kettle through a fifth pipeline, the two ends of the evaporation heat exchanger are connected with a refrigerating machine, the refrigerating machine is structurally characterized in that one end of the evaporation heat exchanger is sequentially connected in series with a gas-liquid separator, a compressor, an oil separator, a condenser, a drying filter, a second cold storage tank, an electromagnetic valve and an expansion valve through a third pipeline, the outer end of the expansion valve is connected with the other end of the evaporation heat exchanger through an eighth pipeline, the refrigerating machine is positioned between the electromagnetic valve and the second cold storage tank and is connected with the third pipeline through the second pipeline, and an electronic expansion valve is arranged on the second pipeline. The work reliability is good.

In-vehicle temperature adjusting device, vehicle air-conditioning device, and battery temperature adjsuting device

Abstract: A vehicle-mounted temperature adjustment device included in a vehicle air-conditioning device includes a low-water-temperature circuit through which low-water-temperature cooling water circulates. In addition, the vehicle-mounted temperature adjustment device has a compressor, a condenser, a subcooling condenser, an expansion valve, which is one example of a first expansion unit, an expansion valve, which is one example of a second expansion unit, and an evaporator and refrigerant-water heat exchanger, and includes a refrigeration circuit that performs temperature adjustment of a temperature-adjustment target. The low-water-temperature circuit has a sub-radiator that releases heat of the low-water-temperature cooling water that has been subjected to heat exchange with refrigerant at the subcooling condenser.

Control method and device for air conditioning system

Abstract: The invention belongs to the technical field of air conditioning, and particularly relates to a control method and device for an air conditioning system. According to the control method and device for the air conditioning system, all temperature parameters of the system after defrosting are acquired, the opening degree of operation of an electronic expansion valve is adjusted timely according to indoor temperature differences delta TIN and outdoor temperature differences delta TOU, the phenomenon of oil blockage of an expansion valve after low temperature defrosting of new refrigerant air conditioning systems such as R290 is effectively avoided, the using comfort of the new refrigerant air conditioning systems is improved, the service life of a compressor and the system is prolonged, and a reference basis is provided for better matching new refrigerants for studying novel compressor engine oil in the future.

Single-effect absorption refrigeration cycle boosted with an ejector-adiabatic absorber using a single solution pump

Abstract: This paper presents a numerical model of a single-effect absorption refrigeration cycle incorporating a triple purpose liquid–vapor ejector acting as pressure booster for refrigerant vapor, adiabatic absorber and controlled solution expansion valve The promising ammonia-lithium nitrate solution is selected as working pair, being able to produce cold at subzero temperatures, thus valid either for air conditioning or industrial refrigeration With the use of the liquid–gas ejector, the absorption pressure becomes higher than the evaporation pressure, besides recovering part of the solution pump energy Results of the simulation show that this innovation behaves like a compressor boosted hybrid cycle without carrying its complexity It allows decreasing the activation temperature (about 15 °C for a recirculation ratio of 3) and increasing the cooling capacity (reaching a gain of about 100% for a generation temperature of 80 °C)

Heat pump water heater

Abstract: PROBLEM TO BE SOLVED: To provide a heat pump water heater that enables improvement of heat exchange efficiency of a heat pump type heat source machine by using condensed water generated in a latent heat recovery type auxiliary heat source machine, shortening of defrosting operation time and other improvement.SOLUTION: A heat pump water heater 1 includes: a heat pump type heat source machine 20 constituted by interconnecting a compressor 21, a heat exchanger 22 for hot water supply, an expansion valve 23 and a heat exchanger 24 for absorbing heat of outside air by using a refrigerant circuit 25; a hot water storage tank 5 for storing hot water heated by the heat exchanger 22 for hot water supply; a combustion type auxiliary heat source machine 10 that is used for heating hot water stored in the hot water storage tank 5 when the temperature of the hot water is low and has a heat exchanger 10d for recovering latent heat; and a neutralizer 31 (storage tank) for storing condensed water generated in the heat exchanger 10d for recovering latent heat. The condensed water in the neutralizer 31 is sent to the heat exchanger 24 for absorbing heat of outside air via a feed passage 32 so as to enable heat exchange with the heat exchanger 24 for absorbing heat of outside air.

Heat pump system

Abstract: PROBLEM TO BE SOLVED: To provide a heat pump system capable of improving an environmental property, convenience and economic efficiency.SOLUTION: A heat pump system includes: a circulation pipeline 10 in which a heating medium circulates; a first heat exchanger 11 for performing heat exchange between the heating medium and first heat exchange object fluid; a second heat exchanger 13 for performing heat exchange between the heating medium and second heat exchange object fluid; a compressor unit 12 for compressing the heating medium; and an expansion valve 14 for expanding the heating medium. A heat pump cycle is formed by arranging the first heat exchanger 11, the compressor unit 12, the second heat exchanger 13 and the expansion valve 14 in this order in a path in the circulation pipeline 10. The compressor unit 12 includes an internal combustion engine 20 and a motor 21. The heating medium is compressed by driving one of the internal combustion engine 20 and the motor 21.

Multi-compartment transport refrigeration system with evaporator isolation valve

Abstract: A multi-compartment transport refrigeration system includes a heat rejecting heat exchanger downstream of a compressor discharge port; a first evaporator expansion device downstream of the heat rejecting heat exchanger; a first evaporator having an first evaporator inlet coupled to the first evaporator expansion device and a first evaporator outlet coupled to the compressor inlet path, the first evaporator for cooling a first compartment; a second evaporator expansion device downstream of the heat rejecting heat exchanger; a second evaporator having a second evaporator inlet coupled to the second evaporator expansion device and a second evaporator outlet coupled to the compressor inlet path, the second evaporator for cooling a second compartment; and a first evaporator outlet isolation valve positioned in an outlet of the first evaporator, the first evaporator outlet isolation valve to prevent migration of refrigerant from the second evaporator outlet to the first evaporator outlet.

Air conditioning system control method and control device

Abstract: The invention belongs to the technical field of air conditioner, in particular to an air conditioning system control method and control device. By acquiring Z refrigerant pressure values P continuously, the opening degree of an electronic expansion valve is adjusted properly according to whether or not X P0 larger than a preset value exist, the situation of expansion valve oil plugging after low-temperature defrosting of R 290 and other novel refrigerant air conditioning systems can be avoided, using comfort of the novel refrigerant air conditioner is improved, the service lives of a compressor and system are guaranteed, and a reference for research of novel compressor oil matching with the novel refrigerant better in the future is provided.

Air conditioner and detection control method and device for abnormal coolant circulation of air conditioner

Abstract: The invention belongs to the technical field of air conditioner control, and provides an air conditioner and a detection control method and device for the abnormal coolant circulation of the air conditioner The method comprises the steps of in the operation process of the air conditioner, obtaining corresponding rated input power from a preset correlated database according to outdoor environment temperature, indoor environment temperature, operation frequency of a compressor and the opening degree of an expansion valve, judging that the coolant circulation is abnormal when the difference between the current air conditioner input power and the rated input power is larger than a power difference reference value, recording the abnormal times, and restarting the compressor to drive the coolant circulation to restore normal after the compressor is stopped for certain time if the abnormal times do not achieve the preset continuous abnormal times; if the normal times achieve the preset continuous abnormal times, showing that the coolant circulation cannot be restored normal, controlling the air conditioner to be stopped to avoid the damage of the compressor, and sending an abnormal prompt to notify a user, thus solving the problem that the air conditioner compressor is damaged due to the fact that the expansion valve of an air conditioner outdoor unit is blocked by a coolant

Electronic expansion valve and control method thereof

Abstract: An electronic expansion valve of an air-conditioning system includes a valve body and an expansion valve controller; the valve body includes a refrigerant channel, a valve pin, and a stepping motor; the stepping motor controls the movement of the valve pin to adjust the size of the opening of the refrigerant channel; the expansion valve controller outputs different control signals according to different operation conditions of the electronic expansion valve; inputting different current to the stepping motor so as to drive the stepping motor to rotate; and controlling the movement of the valve pin to adjust the size of the refrigerant channel. The electronic expansion valve employs different current to drive a stepping motor according to different operation conditions, thus reducing system energy consumption, overcoming abnormal fault of the motor, and extending the service life of the electronic expansion valve.

Thermal management system and method for power battery pack

Abstract: The invention provides a thermal management system and method for a power battery pack. The system comprises a heat pump device and a thermal management unit, wherein the heat pump device comprises a closed loop formed by a compressor, a four-way valve and a liquid storage tank, wherein the four-way valve is arranged between the compressor and the liquid storage tank; the thermal management unit comprises a heat exchange unit and a switching unit, the heat exchange unit comprises an out-car heat exchanger and an in-battery compartment heat exchanger, the switching unit comprises a heating expansion valve and a refrigeration expansion valve, and the four-way valve is connected with the out-car heat exchanger; the heating expansion valve, the refrigeration expansion valve and the in-battery compartment heat exchanger are connected with the out-car heat exchanger in sequence, and the in-battery compartment heat exchanger is further connected to the four-way valve to form a thermal management loop. According to the thermal management system and method for the power battery pack provided by the invention, the heat pump technology is applied to the thermal management of the power battery pack, so that the battery pack can work at the proper environmental temperature, and the unification of the heating and cooling thermal management can be realized.

Indoor and outdoor ambient condition driven system

Abstract: A refrigeration system includes a compressor, a condenser, a receiver, an expansion device, and an evaporator in fluid communication with one another. An electronic condenser pressure control valve is in fluid communication with an outlet of the condenser and operative to control a condition at the outlet of the condenser. A controller is operatively coupled to the electronic condenser pressure control valve, the controller including logic configured to operate the electronic condenser pressure control valve to dynamically float the discharge pressure at the condenser outlet based on at least one of one or more system conditions or one or more ambient condition.

Integrated membrane dehumidification system

Abstract: An air temperature and humidity control device is provided including a first heat pump having a compressor, an expansion valve, a condenser, and an evaporator. The first heat pump has a refrigerant circulating there through. A humidity controller includes a first contactor fluidly coupled to the evaporator and condenser. The first contact includes at least one contact module having a porous sidewall that defines an internal space through which a hygroscopic material flows. A first air flow is in communication with the porous sidewall of the first contactor. The device also has a second heat pump including a first polishing coil. The first polishing coil is substantially aligned with and arranged generally downstream from the first contactor relative to the first air flow.