The Experts below are selected from a list of 24321 Experts worldwide ranked by ideXlab platform
Hong Li Wang - One of the best experts on this subject based on the ideXlab platform.
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Performance Analysis of Two Stage Compression Cycle with an Internal Heat Exchanger
Applied Mechanics and Materials, 2014Co-Authors: Hong Li Wang, Jing Rui TianAbstract:With increasing of the evaporating temperature, the two stage Compression Cycle with an internal exchanger’s COP has an increasing trend. In addition, R744 achieves the highest COP, and the R12 achieves the minimum level. With increasing of the high pressure and the outlet temperature of the condenser, the two stage Compression Cycle has a down trend. In terms of the increasing intermediate pressure, the two stage Cycle with different refrigerants has different performance: R12’s COP has a downtrend with the pressure changing from 1MPa-3MPa, the rest refrigerants all increased first, and then decreased. Except for R12, they all have optimal intermediate pressure.
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Performance Analysis of Single Stage Compression Cycle with a Throttle Valve
Advanced Materials Research, 2013Co-Authors: Jing Rui Tian, Hong Li WangAbstract:With increasing of high pressure, the performances of all kinds refrigerants except for R744 are all declined and transcritical R744 Compression Cycle has an optimum high pressure. With increasing of the evaporating temperature, all Cycle COP is an increasing trend, with increasing of outlet temperature of condenser, the performances of all Cycles are decreased. Under the same comparison conditions, the performance of R134a refrigerant Cycle is superior to the Cycles of other refrigerants, and the Cycle of R11 refrigerant has the worst performance.
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ICICA (2) - Performance Analysis of Transcritical CO2 Compression Cycle
Communications in Computer and Information Science, 2012Co-Authors: Hong Li Wang, Jing Rui Tian, Huiqin LiuAbstract:With the growing awareness of dual threats of global warming and ozone depletion, environmentally benign natural refrigerants have attracted considerable attention. As a natural refrigerant, CO2 is a potential substitute for synthesized refrigerants with favorable environmental properties. In order to improve the performance of the transcritical CO2 Compression Cycle, the mathematical models of three kinds single stage Cycle and three kinds two stage Cycle were developed and the performances were analyzed. The results showed that the optimum intermediate pressure affects the performance of transcritical CO2 two stage Compression Cycle. The system COP increases with the evaporating temperature rises. Oppositely, the COP decreases with the cooled temperature rises. Some fundamental data were obtained for improving Cycle performance and developing the products of CO2 refrigeration air condition and heat pumps.
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Performance Analysis of Transcritical CO2 Two Stage Compression Cycle with an Intercooler (TSCC+IC) and the Cycle with an Expander (TSCE+IC)
Advanced Materials Research, 2012Co-Authors: Jing Rui Tian, Hong Li WangAbstract:In range of high pressure, the performance of two stage Compression Cycle with an expander (TSCE+IC) is better than the two stage Cycle with an intercooler (TSCC+IC). In the Cycle (TSCE+IC), the optimum discharge temperature is 42°C and the highest COP is 3.3, in the Cycle (TSCC+IC), the optimum discharge temperature is 50°C and the highest COP is 3.07. In the Cycle (TSCC+IC), the optimum intermediate pressure is 5.8MPa and the highest COP is 3.08, in the Cycle (TSCE+IC), the optimum intermediate pressure is 6.2MPa and the highest COP is 3.33. With increasing of evaporating temperature or decreasing outlet temperature of gas cooler, the performance of Cycle (TSCE+IC) or Cycle (TSCC+IC) is an increasing trend. Under the same conditions, expander Cycle performance superior to the throttle valve performance. Some fundamental data were obtained for improving Cycle performance and developing the products of CO2 refrigeration air condition and heat pumps.
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theoretical analysis and experimental research on transcritical co2 two stage Compression Cycle with two gas coolers tscc tg and the Cycle with intercooler tscc ic
Energy Conversion and Management, 2011Co-Authors: Jing Rui Tian, Hong Li Wang, Minxia LiAbstract:Abstract As one of the natural refrigerants, CO 2 is a potential substitute for synthesized refrigerants with favorable environmental properties. In order to improve the performance of the CO 2 transcritical Compression Cycle, the performance of the two stage Compression Cycle with two gas coolers (TSCC + TG) and the two stage Compression Cycle with intercooler (TSCC + IC) were analyzed, respectively. Under the given calculation condition, the optimum intermediate pressure of the Cycle TSCC + TG and the TSCC + IC are 7.09 MPa and 5.89 MPa, and the maximal COP are 2.77 and 3.08, respectively. Range of the given evaporating temperature and outlet temperature of gas cooler, the experimental testing shows that the performance of Cycle TSCC + IC are 11.88% and 10.87% better than that of the Cycle TSCC + TG, respectively. Range of the given inlet temperature and cooling water volume flow of gas cooler, the refrigeration COP (COP c ) and heat COP (COP h ) of the Cycle TSCC + IC are average 10.97% and 4.39% higher than that of the Cycle TSCC + TG. Range of the given inlet temperature and chilled water volume flow of evaporator, the refrigeration COP (COP c ) and heat COP (COP h ) of the Cycle TSCC + IC are average 10.71% and 3.67% higher than that of the Cycle TSCC + TG, respectively. The error between theoretical calculation and experimental testing is not exceeds 20%.
Andrew G. Alleyne - One of the best experts on this subject based on the ideXlab platform.
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LMI control design for nonlinear vapor Compression Cycle systems
Volume 2: Legged Locomotion; Mechatronic Systems; Mechatronics; Mechatronics for Aquatic Environments; MEMS Control; Model Predictive Control; Modelin, 2012Co-Authors: Neera Jain, Andrew G. AlleyneAbstract:To effectively control vapor Compression Cycle (VCC) systems whose dynamics are highly nonlinear, it is necessary to develop plant models and control laws for different operating regions. This paper presents a first-principles modeling framework that captures four operation modes over the operating envelope to construct an invariant-order switched system. To synthesize a multi-input multi-output (MIMO) control system, the Linear Quadratic Regulator (LQR) technique is framed as a control optimization problem with Linear Matrix Inequality (LMI) constraints which can be simultaneously solved for the set of considered linear systems. Stability and performance characteristics of the controlled system are guaranteed using a common quadratic Lyapunov function. Simulation results in a case study show that the LMI-based controller can maintain system operation at optimal set-points with mode switching over a wide operating envelope.Copyright © 2012 by ASME
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Thermodynamics-based optimization and control of vapor-Compression Cycle operation: Optimization criteria
Proceedings of the 2011 American Control Conference, 2011Co-Authors: Neera Jain, Andrew G. AlleyneAbstract:This paper investigates multiple degree of freedom (MDOF) optimization of steady-state vapor-Compression Cycle (VCC) operation. Five degrees of freedom (DOFs) of the VCC are optimized using an objective function which minimizes the rate of exergy destruction in the Cycle. The use of exergy is motivated by its ability to capture the physics of both the first and second laws of thermodynamics in a single property. A case study is considered in which the optimization is applied to a commercial truck transport refrigeration system (TTRS). The results suggest that by using the optimal set points generated by the exergy-based objective function, an increase of 52.5% in COP can be achieved over nominal operation. In particular, the optimization results highlight the regulation of evaporator and condenser pressure as critical parameters in improving the efficiency of steady-state Cycle operation.
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A dynamic model of a vapor Compression Cycle with shut-down and start-up operations
International Journal of Refrigeration-revue Internationale Du Froid, 2010Co-Authors: Andrew G. AlleyneAbstract:Abstract This paper presents an advanced switched modeling approach for vapor Compression Cycle (VCC) systems used in Air Conditioning and Refrigeration. Building upon recent work ( McKinley and Alleyne, 2008 ), a complete dynamic VCC model is presented that is able to describe the severe transient behaviors in heat exchangers (condenser/evaporator), while maintaining the moving-boundary framework, under compressor shut-down and start-up operations. The heat exchanger models retain a constant structure, but accommodate different model representations. Novel switching schemes between different representations and pseudo-state variables are introduced to accommodate the transitions of dynamic states in heat exchangers while keeping track of the vapor and liquid refrigerant zones during the stop–start transients. Two model validation studies on an experimental system show that the complete dynamic model developed in Matlab/Simulink can well predict the system dynamics in shut-down and start-up transients.
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decentralized feedback structures of a vapor Compression Cycle system
IEEE Transactions on Control Systems and Technology, 2010Co-Authors: Neera Jain, Bin Li, M Keir, Brandon Hencey, Andrew G. AlleyneAbstract:In vapor Compression Cycle systems, it is desirable to effectively control the thermodynamic Cycle by controlling the thermodynamic states of the refrigerant. By controlling the thermodynamic states with an inner loop, supervisory algorithms can manage critical functions and objectives such as maintaining superheat and maximizing the coefficient of performance. In practice, it is generally preferred to tune multiple single-input-single-output (SISO) control inner loops rather than a single multiple-input-multiple-output control inner loop. This paper presents a process by which a simplified feedback control structure, amenable to a decoupled SISO control loop design, may be identified. In particular, the many possible candidate input-output (I/O) pairs for decentralized control are sorted via a decoupling metric, called the relative gain array number. From a reduced set of promising candidate I/O pairs, engineering insight is applied to arrive at the most effective pairings successfully verified on an experimental air-conditioning-and-refrigeration test stand.
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a full dynamic model of a hvac vapor Compression Cycle interacting with a dynamic environment
American Control Conference, 2009Co-Authors: Andrew G. AlleyneAbstract:This paper presents an advanced switched model approach for vapor Compression Cycle (VCC) systems with shut-down and start-up operations. Building upon recent work [2], a full dynamic system model with switched moving-boundary components is presented that is able to accommodate severe transients in heat exchanger dynamics. These new switched heat exchanger models are created with uniform model structures, but with combinations of different model representations. It is shown that switching schemes between different representations handle the transitions of dynamic states while keeping track of vapor and liquid refrigerant regions during stop-start transients. The dynamic system model is created in Matlab/Simulink and is successfully verified on an experimental test stand. A combined VCC/environment is simulated with a hysteretic temperature controller in a case study. The qualitative accuracy of the case study results demonstrate the potential for this dynamic switched model approach for controller designs, including compressor cycling, in VCC systems.
Siew Hwa Chan - One of the best experts on this subject based on the ideXlab platform.
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energy analysis of a hybrid pemfc solar energy residential micro cchp system combined with an organic rankine Cycle and vapor Compression Cycle
Energy Conversion and Management, 2017Co-Authors: Huawei Chang, Yao Zheng, Xi Chen, Zhengkai Tu, Siew Hwa ChanAbstract:Abstract A residential combined cooling heating and power (CCHP) system based on proton exchange membrane fuel cell (PEMFC) and solar energy is proposed. This system mainly consists of a PEMFC subsystem, an organic Rankine Cycle/domestic hot water (ORC/DHW) subsystem and a vapor Compression Cycle (VCC) subsystem. The electric power of the system is about 8 kW, and the cooling/heating capacity is 14.5 kW under rated operating conditions. Mathematical models are developed for each subsystem, and their associated costs and CCHP efficiency are estimated based on assumptions made. The effects of current density, operating temperature, solar radiation and ambient temperature are analyzed. The results show that current density, solar radiation and ambient temperature have a significant impact on CCHP efficiency, while the impact of operating temperature is relatively small. CCHP efficiency increases with current density both in summer and in winter, reaching 75.4% and 85.0%, respectively. The efficiency decreases with the increase of ambient temperature in summer, while in the winter it increases. In addition, the CCHP system can reduce to a combined cooling and heating (CCH) system if the PEMFC subsystem is shutdown or reduce to a combined heating and power (CHP) system when the solar radiation intensity is close to zero.
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energy analysis of a hybrid pemfc solar energy residential micro cchp system combined with an organic rankine Cycle and vapor Compression Cycle
Energy Conversion and Management, 2017Co-Authors: Huawei Chang, Yao Zheng, Xi Chen, Zhongmin Wan, Shuiming Shu, Siew Hwa ChanAbstract:Abstract A residential combined cooling heating and power (CCHP) system based on proton exchange membrane fuel cell (PEMFC) and solar energy is proposed. This system mainly consists of a PEMFC subsystem, an organic Rankine Cycle/domestic hot water (ORC/DHW) subsystem and a vapor Compression Cycle (VCC) subsystem. The electric power of the system is about 8 kW, and the cooling/heating capacity is 14.5 kW under rated operating conditions. Mathematical models are developed for each subsystem, and their associated costs and CCHP efficiency are estimated based on assumptions made. The effects of current density, operating temperature, solar radiation and ambient temperature are analyzed. The results show that current density, solar radiation and ambient temperature have a significant impact on CCHP efficiency, while the impact of operating temperature is relatively small. CCHP efficiency increases with current density both in summer and in winter, reaching 75.4% and 85.0%, respectively. The efficiency decreases with the increase of ambient temperature in summer, while in the winter it increases. In addition, the CCHP system can reduce to a combined cooling and heating (CCH) system if the PEMFC subsystem is shutdown or reduce to a combined heating and power (CHP) system when the solar radiation intensity is close to zero.
Huawei Chang - One of the best experts on this subject based on the ideXlab platform.
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energy analysis of a hybrid pemfc solar energy residential micro cchp system combined with an organic rankine Cycle and vapor Compression Cycle
Energy Conversion and Management, 2017Co-Authors: Huawei Chang, Yao Zheng, Xi Chen, Zhengkai Tu, Siew Hwa ChanAbstract:Abstract A residential combined cooling heating and power (CCHP) system based on proton exchange membrane fuel cell (PEMFC) and solar energy is proposed. This system mainly consists of a PEMFC subsystem, an organic Rankine Cycle/domestic hot water (ORC/DHW) subsystem and a vapor Compression Cycle (VCC) subsystem. The electric power of the system is about 8 kW, and the cooling/heating capacity is 14.5 kW under rated operating conditions. Mathematical models are developed for each subsystem, and their associated costs and CCHP efficiency are estimated based on assumptions made. The effects of current density, operating temperature, solar radiation and ambient temperature are analyzed. The results show that current density, solar radiation and ambient temperature have a significant impact on CCHP efficiency, while the impact of operating temperature is relatively small. CCHP efficiency increases with current density both in summer and in winter, reaching 75.4% and 85.0%, respectively. The efficiency decreases with the increase of ambient temperature in summer, while in the winter it increases. In addition, the CCHP system can reduce to a combined cooling and heating (CCH) system if the PEMFC subsystem is shutdown or reduce to a combined heating and power (CHP) system when the solar radiation intensity is close to zero.
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energy analysis of a hybrid pemfc solar energy residential micro cchp system combined with an organic rankine Cycle and vapor Compression Cycle
Energy Conversion and Management, 2017Co-Authors: Huawei Chang, Yao Zheng, Xi Chen, Zhongmin Wan, Shuiming Shu, Siew Hwa ChanAbstract:Abstract A residential combined cooling heating and power (CCHP) system based on proton exchange membrane fuel cell (PEMFC) and solar energy is proposed. This system mainly consists of a PEMFC subsystem, an organic Rankine Cycle/domestic hot water (ORC/DHW) subsystem and a vapor Compression Cycle (VCC) subsystem. The electric power of the system is about 8 kW, and the cooling/heating capacity is 14.5 kW under rated operating conditions. Mathematical models are developed for each subsystem, and their associated costs and CCHP efficiency are estimated based on assumptions made. The effects of current density, operating temperature, solar radiation and ambient temperature are analyzed. The results show that current density, solar radiation and ambient temperature have a significant impact on CCHP efficiency, while the impact of operating temperature is relatively small. CCHP efficiency increases with current density both in summer and in winter, reaching 75.4% and 85.0%, respectively. The efficiency decreases with the increase of ambient temperature in summer, while in the winter it increases. In addition, the CCHP system can reduce to a combined cooling and heating (CCH) system if the PEMFC subsystem is shutdown or reduce to a combined heating and power (CHP) system when the solar radiation intensity is close to zero.
Jing Rui Tian - One of the best experts on this subject based on the ideXlab platform.
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Performance Analysis of Two Stage Compression Cycle with an Internal Heat Exchanger
Applied Mechanics and Materials, 2014Co-Authors: Hong Li Wang, Jing Rui TianAbstract:With increasing of the evaporating temperature, the two stage Compression Cycle with an internal exchanger’s COP has an increasing trend. In addition, R744 achieves the highest COP, and the R12 achieves the minimum level. With increasing of the high pressure and the outlet temperature of the condenser, the two stage Compression Cycle has a down trend. In terms of the increasing intermediate pressure, the two stage Cycle with different refrigerants has different performance: R12’s COP has a downtrend with the pressure changing from 1MPa-3MPa, the rest refrigerants all increased first, and then decreased. Except for R12, they all have optimal intermediate pressure.
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Performance Analysis of Single Stage Compression Cycle with a Throttle Valve
Advanced Materials Research, 2013Co-Authors: Jing Rui Tian, Hong Li WangAbstract:With increasing of high pressure, the performances of all kinds refrigerants except for R744 are all declined and transcritical R744 Compression Cycle has an optimum high pressure. With increasing of the evaporating temperature, all Cycle COP is an increasing trend, with increasing of outlet temperature of condenser, the performances of all Cycles are decreased. Under the same comparison conditions, the performance of R134a refrigerant Cycle is superior to the Cycles of other refrigerants, and the Cycle of R11 refrigerant has the worst performance.
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ICICA (2) - Performance Analysis of Transcritical CO2 Compression Cycle
Communications in Computer and Information Science, 2012Co-Authors: Hong Li Wang, Jing Rui Tian, Huiqin LiuAbstract:With the growing awareness of dual threats of global warming and ozone depletion, environmentally benign natural refrigerants have attracted considerable attention. As a natural refrigerant, CO2 is a potential substitute for synthesized refrigerants with favorable environmental properties. In order to improve the performance of the transcritical CO2 Compression Cycle, the mathematical models of three kinds single stage Cycle and three kinds two stage Cycle were developed and the performances were analyzed. The results showed that the optimum intermediate pressure affects the performance of transcritical CO2 two stage Compression Cycle. The system COP increases with the evaporating temperature rises. Oppositely, the COP decreases with the cooled temperature rises. Some fundamental data were obtained for improving Cycle performance and developing the products of CO2 refrigeration air condition and heat pumps.
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Performance Analysis of Transcritical CO2 Two Stage Compression Cycle with an Intercooler (TSCC+IC) and the Cycle with an Expander (TSCE+IC)
Advanced Materials Research, 2012Co-Authors: Jing Rui Tian, Hong Li WangAbstract:In range of high pressure, the performance of two stage Compression Cycle with an expander (TSCE+IC) is better than the two stage Cycle with an intercooler (TSCC+IC). In the Cycle (TSCE+IC), the optimum discharge temperature is 42°C and the highest COP is 3.3, in the Cycle (TSCC+IC), the optimum discharge temperature is 50°C and the highest COP is 3.07. In the Cycle (TSCC+IC), the optimum intermediate pressure is 5.8MPa and the highest COP is 3.08, in the Cycle (TSCE+IC), the optimum intermediate pressure is 6.2MPa and the highest COP is 3.33. With increasing of evaporating temperature or decreasing outlet temperature of gas cooler, the performance of Cycle (TSCE+IC) or Cycle (TSCC+IC) is an increasing trend. Under the same conditions, expander Cycle performance superior to the throttle valve performance. Some fundamental data were obtained for improving Cycle performance and developing the products of CO2 refrigeration air condition and heat pumps.
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theoretical analysis and experimental research on transcritical co2 two stage Compression Cycle with two gas coolers tscc tg and the Cycle with intercooler tscc ic
Energy Conversion and Management, 2011Co-Authors: Jing Rui Tian, Hong Li Wang, Minxia LiAbstract:Abstract As one of the natural refrigerants, CO 2 is a potential substitute for synthesized refrigerants with favorable environmental properties. In order to improve the performance of the CO 2 transcritical Compression Cycle, the performance of the two stage Compression Cycle with two gas coolers (TSCC + TG) and the two stage Compression Cycle with intercooler (TSCC + IC) were analyzed, respectively. Under the given calculation condition, the optimum intermediate pressure of the Cycle TSCC + TG and the TSCC + IC are 7.09 MPa and 5.89 MPa, and the maximal COP are 2.77 and 3.08, respectively. Range of the given evaporating temperature and outlet temperature of gas cooler, the experimental testing shows that the performance of Cycle TSCC + IC are 11.88% and 10.87% better than that of the Cycle TSCC + TG, respectively. Range of the given inlet temperature and cooling water volume flow of gas cooler, the refrigeration COP (COP c ) and heat COP (COP h ) of the Cycle TSCC + IC are average 10.97% and 4.39% higher than that of the Cycle TSCC + TG. Range of the given inlet temperature and chilled water volume flow of evaporator, the refrigeration COP (COP c ) and heat COP (COP h ) of the Cycle TSCC + IC are average 10.71% and 3.67% higher than that of the Cycle TSCC + TG, respectively. The error between theoretical calculation and experimental testing is not exceeds 20%.