Research on the control laws of the electronic expansion valve for an air source heat pump water hea

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.

[1]  Alessandro Beghi,et al.  A simulation environment for dry-expansion evaporators with application to the design of autotuning control algorithms for electronic expansion valves , 2009 .

[2]  Chih Wu,et al.  A new heat recovery technique for air-conditioning/heat-pump system , 2008 .

[3]  Arif Hepbasli,et al.  A review of heat pump water heating systems , 2009 .

[4]  Hua Li,et al.  Feedforward control of capacity and superheat for a variable speed refrigeration system , 2009 .

[5]  Tin-Tai Chow,et al.  Domestic air-conditioner and integrated water heater for subtropical climate , 2003 .

[6]  Honghyun Cho,et al.  Mass flow characteristics and empirical modeling of R22 and R410A flowing through electronic expansion valves , 2007 .

[7]  Zhijiu Chen,et al.  A new method for controlling refrigerant flow in automobile air conditioning , 2004 .

[8]  Shi Lin,et al.  Refrigerant flow characteristics of electronic expansion valve based on thermodynamic analysis and experiment , 2008 .

[9]  C. Changenet,et al.  Predictive functional control of an expansion valve for minimizing the superheat of an evaporator , 2010 .

[10]  Jili Zhang,et al.  Experimental study on a duty ratio fuzzy control method for fan-coil units , 2011 .

[11]  Shaohua Tan,et al.  Gain scheduling: from conventional to neuro-fuzzy , 1997, Autom..

[12]  Terence C. Fogarty,et al.  A comparative study of artificial neural networks and rule-based techniques in the development of a computer-aided control system , 1994 .

[13]  Haralambos Sarimveis,et al.  Selection of window sizes for optimizing occupational comfort and hygiene based on computational fluid dynamics and neural networks , 2011 .

[14]  M. Hosoz,et al.  Comparative performance of an automotive air conditioning system using fixed and variable capacity compressors , 2010 .

[15]  Chen Wen.  Control Algorithm of Electronic Expansion Valve in Evaporator Superheat Regulation , 2001 .

[16]  C. H. Chiou,et al.  The application of fuzzy control on energy saving for multi-unit room air-conditioners , 2009 .

[17]  Ruzhu Wang,et al.  Transient characteristics and performance analysis of a vapor compression air conditioning system with condensing heat recovery , 2010 .

[18]  Zhen Lu,et al.  Experimental analysis of control loops with different delay times in the supply air system of a radiator test rig , 2011 .

[19]  Savvas A. Tassou,et al.  VARIABLE-SPEED CAPACITY CONTROL IN REFRIGERATION SYSTEMS , 1996 .

[20]  Li Zheng,et al.  Indoor thermal comfort characteristics under the control of a direct expansion air conditioning unit having a variable-speed compressor and a supply air fan , 2009 .

[21]  Chen Wen-yong.  Electronic Expansion Valve Control during the Start-up of Refrigeration System , 2005 .

[22]  Savvas A. Tassou,et al.  Investigation of the effects of thermostatic and electronic expansion valves on the steady-state and transient performance of commercial chillers. , 1993 .

[23]  Yong Chan Kim,et al.  Capacity modulation of an inverter-driven multi-air conditioner using electronic expansion valves , 2003 .

[24]  Masud Behnia,et al.  Seasonal Performance Rating of Heat Pump Water Heaters , 2004 .

[25]  Ruzhu Wang,et al.  Experimental performance analysis on a direct-expansion solar-assisted heat pump water heater , 2007 .

[26]  Min-Soo Kim,et al.  Transient thermal behavior of a water heater system driven by a heat pump , 2004 .

[27]  Shiming Deng,et al.  Improved indoor thermal comfort during defrost with a novel reverse-cycle defrosting method for air source heat pumps , 2010 .