The Experts below are selected from a list of 4221 Experts worldwide ranked by ideXlab platform
R Z Wang - One of the best experts on this subject based on the ideXlab platform.
-
research on the control laws of the electronic Expansion Valve for an air source heat pump water heater
Building and Environment, 2011Co-Authors: Mingliu Jiang, J Y Wu, R Z Wang, Y X XuAbstract:Compared to the conventional air conditioner, the air source heat pump water heater (ASHPWH) possesses wider operating ranges and more dramatic changes in working conditions. Conversely, traditional throttle devices, such as the thermostatic Expansion Valve (TEV) and capillary tube, are restricted by narrow regulating ranges in refrigerant mass flow rate and lagging response to the superheat. This article incorporates a novel dual-fuzzy-controller to regulate the electronic Expansion Valve (EEV) specialized for the ASHPWH system. The study analyzes the effects of the EEV initial opening and the target superheat on the performance of the ASHPWH. Moreover, this research proposes a fuzzy control method of selecting the initial opening and the target superheat on the basis of the ambient temperature and water temperature, and employs superheat error (e) and the derivation of superheat error (ec) as the input variables of the fuzzy controller B to regulate the opening of the EEV during steady running process. To improve self-adaptability of the fuzzy controller, a rule modifier and a gain scheduler are introduced. In order to quantitatively reflect the difference in the performance between the TEV-controlled system and EEV-controlled one, experimental comparison between the EEV and the TEV is presented. Results demonstrate that both the stability and efficiency of the ASHPWH can be improved significantly by the EEV.
-
transient characteristics and performance analysis of a vapor compression air conditioning system with condensing heat recovery
Energy and Buildings, 2010Co-Authors: Mingliu Jiang, Jing Yi Wu, Yu Xiong Xu, R Z WangAbstract:The objective of this study is to evaluate the influence of condensing heat recovery on the dynamic behavior and performance of air conditioners. The article includes a test procedure utilized to evaluate the condensing heat recovery system, relevant experimental results, a detail analysis of the mechanisms, and improvement measure on such a system. The experimental results indicate that although the condensing heat recovery has a negative effect on the cooling capacity at the start of the heat recovery process, the average cooling coefficient of performance (COP) of the system can be improved. The study also incorporates a control scheme of the electronic Expansion Valve (EEV) of the condensing heat recovery system. The experimental comparison between the EEV and the thermostatic Expansion Valve (TEV) demonstrates that the EEV has better performance in both stability and efficiency in the condensing heat recovery system.
Mingliu Jiang - One of the best experts on this subject based on the ideXlab platform.
-
research on the control laws of the electronic Expansion Valve for an air source heat pump water heater
Building and Environment, 2011Co-Authors: Mingliu Jiang, J Y Wu, R Z Wang, Y X XuAbstract:Compared to the conventional air conditioner, the air source heat pump water heater (ASHPWH) possesses wider operating ranges and more dramatic changes in working conditions. Conversely, traditional throttle devices, such as the thermostatic Expansion Valve (TEV) and capillary tube, are restricted by narrow regulating ranges in refrigerant mass flow rate and lagging response to the superheat. This article incorporates a novel dual-fuzzy-controller to regulate the electronic Expansion Valve (EEV) specialized for the ASHPWH system. The study analyzes the effects of the EEV initial opening and the target superheat on the performance of the ASHPWH. Moreover, this research proposes a fuzzy control method of selecting the initial opening and the target superheat on the basis of the ambient temperature and water temperature, and employs superheat error (e) and the derivation of superheat error (ec) as the input variables of the fuzzy controller B to regulate the opening of the EEV during steady running process. To improve self-adaptability of the fuzzy controller, a rule modifier and a gain scheduler are introduced. In order to quantitatively reflect the difference in the performance between the TEV-controlled system and EEV-controlled one, experimental comparison between the EEV and the TEV is presented. Results demonstrate that both the stability and efficiency of the ASHPWH can be improved significantly by the EEV.
-
transient characteristics and performance analysis of a vapor compression air conditioning system with condensing heat recovery
Energy and Buildings, 2010Co-Authors: Mingliu Jiang, Jing Yi Wu, Yu Xiong Xu, R Z WangAbstract:The objective of this study is to evaluate the influence of condensing heat recovery on the dynamic behavior and performance of air conditioners. The article includes a test procedure utilized to evaluate the condensing heat recovery system, relevant experimental results, a detail analysis of the mechanisms, and improvement measure on such a system. The experimental results indicate that although the condensing heat recovery has a negative effect on the cooling capacity at the start of the heat recovery process, the average cooling coefficient of performance (COP) of the system can be improved. The study also incorporates a control scheme of the electronic Expansion Valve (EEV) of the condensing heat recovery system. The experimental comparison between the EEV and the thermostatic Expansion Valve (TEV) demonstrates that the EEV has better performance in both stability and efficiency in the condensing heat recovery system.
Y X Xu - One of the best experts on this subject based on the ideXlab platform.
-
research on the control laws of the electronic Expansion Valve for an air source heat pump water heater
Building and Environment, 2011Co-Authors: Mingliu Jiang, J Y Wu, R Z Wang, Y X XuAbstract:Compared to the conventional air conditioner, the air source heat pump water heater (ASHPWH) possesses wider operating ranges and more dramatic changes in working conditions. Conversely, traditional throttle devices, such as the thermostatic Expansion Valve (TEV) and capillary tube, are restricted by narrow regulating ranges in refrigerant mass flow rate and lagging response to the superheat. This article incorporates a novel dual-fuzzy-controller to regulate the electronic Expansion Valve (EEV) specialized for the ASHPWH system. The study analyzes the effects of the EEV initial opening and the target superheat on the performance of the ASHPWH. Moreover, this research proposes a fuzzy control method of selecting the initial opening and the target superheat on the basis of the ambient temperature and water temperature, and employs superheat error (e) and the derivation of superheat error (ec) as the input variables of the fuzzy controller B to regulate the opening of the EEV during steady running process. To improve self-adaptability of the fuzzy controller, a rule modifier and a gain scheduler are introduced. In order to quantitatively reflect the difference in the performance between the TEV-controlled system and EEV-controlled one, experimental comparison between the EEV and the TEV is presented. Results demonstrate that both the stability and efficiency of the ASHPWH can be improved significantly by the EEV.
H.o. Al-nizari - One of the best experts on this subject based on the ideXlab platform.
-
Investigation of the steady state and transient performance of a reciprocating chiller equipped with an electronic Expansion Valve
Heat Recovery Systems and Chp, 2003Co-Authors: Savvas A. Tassou, H.o. Al-nizariAbstract:Abstract This paper presents the results of experimental investigations into the performance of a chiller equipped with an electronic Expansion Valve under steady state and transient conditions. The tests were carried out in the laboratory on a 25kW nomimal capacity chiller both during cold start and hot start. For both start-up cases, the response of the chiller in terms of cooling capacity is very fast, leading to low on/off cycling losses. The superheat setting of the Expansion Valve influences both the transient and steady state performance of the chiller. Optimum refrigerant flow control can be achieved by integrating the control of the Expansion Valve into an overall microprocessor-based control strategy for the chiller.
-
Investigation of the effects of thermostatic and electronic Expansion Valves on the steady-state and transient performance of commercial chillers.
International Journal of Refrigeration-revue Internationale Du Froid, 2003Co-Authors: Savvas A. Tassou, H.o. Al-nizariAbstract:Abstract This paper investigates the steady-state performance and transient response of a commercial fixed-speed on-off controlled chiller and presents comparative performance results obtained during operation with a thermostatic and with an electronic Expansion Valve. The aim was to establish the effect of the two Valves on the transient and steady-state performance of the chiller and to quantify the effects of on-off cycling losses during part-load operation. The results indicate that the chiller has a very fast response during start-up and that cycling losses are very low. The thermostatic Expansion Valve gives a slightly faster response than the electronic Expansion Valve with the penalty, however, of less stable operation with larger superheat oscillations at steady-state conditions.
Roger R. Schmidt - One of the best experts on this subject based on the ideXlab platform.
-
Effect of the Location and the Properties of Thermostatic Expansion Valve Sensor Bulb on the Stability of a Refrigeration System
Journal of Heat Transfer-transactions of The Asme, 2005Co-Authors: Veerendra Mulay, Dereje Agonafer, Amit Kulkarni, Roger R. SchmidtAbstract:The combination of increased power dissipation and increased packaging density has led to substantial increases in chip and module heat flux in high-end computers. The challenge has been to limit the rise in chip temperature. In the past, virtually all commercial computers were designed to operate at temperatures above the ambient. However, researchers have identified the advantages of operating electronics at low temperatures. The primary purpose of low-temperature cooling using a vapor compression system are faster switching times of semiconductor devices, increased circuit speed due to lower electrical resistance of interconnecting materials, and a reduction in thermally induced failures of devices and components. The current research focuses on IBM's mainframe, which uses a conventional refrigeration system to maintain chip temperatures below that of comparable air-cooled systems, but well above cryogenic temperatures. Although performance has been the key driver in the use of this technology, the second major reason for designing a system with low-temperature cooling is the improvement achieved in reliability to counteract detrimental effects, which rise as technology is pushed to the extremes. A mathematical model is developed to determine the time constant for an Expansion Valve sensor bulb. This time constant varies with variation in the thermophysical properties of the sensor element; that is, bulb size and bulb liquid. An experimental bench is built to study the effect of variation of evaporator outlet superheat on system performance. The heat load is varied from no load to full load (I KW) to find out the system response at various loads. Experimental investigation is also done to see how the changes in thermophysical properties of the liquid in the sensor bulb of the Expansion Valve affect the overall system performance. Different types of thermostatic Expansion Valves are tested to investigate that bulb size, bulb constant, and bulb location have significant effects on the behavior of the system
-
Effect of the thermostatic Expansion Valve characteristics on the stability of a refrigeration system
Heat Transfer Volume 2, 2003Co-Authors: Veerendra Mulay, Dereje Agonafer, Roger R. SchmidtAbstract:The combination of increased power dissipation and increased packaging density has led to substantial increases in chip and module heat flux in high-end computers. The challenge has been to limit the rise in chip temperature. In the past virtually all-commercial computers were designed to operate at temperatures above the ambient. However researchers have identified the advantages of operating electronics at low temperatures. The primary purpose of low temperature cooling using vapor compression system are faster switching times of semiconductor devices, increased circuit speed due to lower electrical resistance of interconnecting materials, and a reduction in thermally induced failures of devices and components. Achievable performance improvements range from 1 to 3% for every 10°C lower transistor temperature, depending on the doping characteristics of the chip. The current research focuses on IBM’s mainframe, which uses a conventional refrigeration system to maintain chip temperatures below that of comparable air-cooled systems, but well above cryogenic temperatures. Although performance has been the key driver in the use of this technology, the second major reason for designing a system with low temperature cooling is the improvement achieved in reliability to counteract detrimental effects, which rise as technology is pushed to the extremes. A mathematical model is developed to determine the time constant for Expansion Valve sensor blub. This time constant varies with variation in thermo-physical properties of sensor element that is bulb size and blub liquid. An experimental bench is built to study the effect of variation of evaporator outlet superheat on system performance. The heat load is varied from no load to full load (1KW) to find out the system response at various loads. Experimental investigation is also done to see how the changes in thermo-physical properties of the liquid in sensor bulb of Expansion Valve affect the overall system performance. Different types of thermostatic Expansion Valves are tested to investigate that bulb size; bulb constant and bulb location have significant effect on the behavior of the system. Thermal resistance between the bulb and evaporator return line can considerably affect the system stability and by increasing the thermal resistance, the stability can be further increased.Copyright © 2003 by ASME
