The Experts below are selected from a list of 12000 Experts worldwide ranked by ideXlab platform
Fredrik Haglind - One of the best experts on this subject based on the ideXlab platform.
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design of centrifugal Compressors for heat pump systems
Applied Energy, 2018Co-Authors: Andrea Meroni, Benjamin Zuhlsdorf, Brian Elmegaard, Fredrik HaglindAbstract:Abstract This work presents a mean-line model of a centrifugal Compressor and a method for a coupled optimization with a heat pump system. The Compressor model was validated with five test cases from the open literature including the working fluids: air, refrigerant R-134a and carbon dioxide. Afterwards, the Compressor model was coupled and optimized with that of a heat pump cycle supplying steam at 150 °C. Two cycle configurations were considered: an open-loop system using steam, and a closed-loop system with five other working fluid candidates. The Compressor was designed using a multi-objective optimization algorithm, which seeks to maximize simultaneously the cycle coefficient of performance and the supplied heat flow rate. The method employed in this work considers the possible trade-offs regarding cycle and Compressor design criteria, and can be used to identify cost-effective solutions for the next generation of heat pumps. The obtained results suggest that a two-Stage Compressor using steam yields the highest values of coefficient of performance and heat supply, and at the same time requires a more challenging Compressor design.
Yipan Deng - One of the best experts on this subject based on the ideXlab platform.
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investigation on cooling efficiency of a 3d printed integrated inter cooler applicable to a miniature multi Stage Compressor
International Journal of Refrigeration-revue Internationale Du Froid, 2019Co-Authors: Yipan Deng, Na Miao, Yinshui Liu, Xiaomin ZhaiAbstract:Abstract Inter cooler plays an extremely importance role in improving the volumetric efficiency and isentropic efficiency of multi-Stage Compressor. For a miniature multi-Stage Compressor with compact and lightweight structure, conventional inter coolers such as winding copper or stainless steel tubes are incompetent due to their relatively large dimension. A 3D-printed integrated inter cooler with complex channels and compact size is proposed. Selective laser melting process technology is applied due to its high molding precision. A numerical investigation on the cooling efficiency of the inter cooler is carried out. A comprehensive comparison of the overall cooling efficiency is conducted and optimal parameters are obtained for cooling down the inter-Stage gas as much as possible. It turns out that sufficient cooling can be obtained when the coolant flow through the inter cooler with a flow rate above 0.2 L/min. Temperature of coolant influences the outlet gas temperature of all Stages most significantly.
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efficiency evaluation of a miniature multi Stage Compressor under insufficient inter Stage cooling conditions
International Journal of Refrigeration-revue Internationale Du Froid, 2019Co-Authors: Yinshui Liu, Na Miao, Yipan DengAbstract:Abstract A miniature multi-Stage Compressor (MMSC) with an integrated inter-Stage cooler has been proposed. This study aims to evaluate the efficiency of each Stage of the MMSC under insufficient inter-Stage cooling conditions through numerical simulation. The results show that the volumetric efficiency of first-Stage, second-Stage, third-Stage and fourth-Stage reduced by an average of 1.43%, 1.86%, 2.32%, and 2.56% respectively as suction temperature increases every 10 °C, indicating that the temperature has more remarkable influences on the volumetric efficiency with the increase of pressure and the decrease of cylinder diameter. For every 10 °C increase in temperature, the isentropic efficiencies are all reduced by about 1%. And it should be noted that when the suction temperatures of the second, third, fourth Stage cylinder exceed 120 °C, 70 °C, and 50 °C, respectively, the valve flutters severely, indicating that the valve has a poor applicability to the current operating conditions.
Ahrens, Marcel Ulrich - One of the best experts on this subject based on the ideXlab platform.
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Experimental evaluation of a water based high temperature heat pump with novel high pressure lift turbo Compressors
'Siirt Universitesi Sosyal Bilimler Enstitusu Dergisi', 2020Co-Authors: Verpe, Espen Halvorsen, Schlemminger Christian, Bantle Michael, Ahrens, Marcel UlrichAbstract:This paper evaluates a water based (R718) high temperature heat pump with novel high-pressure lift turbo Compressors. The first Stage turbo Compressor is designed for steam compression and the second Stage is designed for air, both are based on economic standard components from the automotive industry. A 500 kW Compressor test rig was built by SINTEF to test the 2-Stage configuration in superheated steam conditions. Compressor efficiency and system COP was calculated based on measurements from the test rig. Also, Compressor maps for the two Compressors was created. For the 1st Stage Compressor, the maximum isentropic efficiency was 67% and maximum pressure ratio 2.4. The second Stage yielded 77% and 2.0. The two-Stage configuration was able to produce 4.23 bar steam, from atmospheric inlet conditions. The system COP corresponded to 4.5 and a Carnot efficiency of 49.5 %. Keywords: Heat pumps, HTHP, Water R718, turbo Compressor, energy efficiency, steam productio
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Experimental evaluation of a water based high temperature heat pump with novel high pressure lift turbo Compressors
IIR, 2020Co-Authors: Verpe, Espen Halvorsen, Schlemminger Christian, Bantle Michael, Ahrens, Marcel UlrichAbstract:This paper evaluates a water based (R718) high temperature heat pump with novel high-pressure lift turbo Compressors. The first Stage turbo Compressor is designed for steam compression and the second Stage is designed for air, both are based on economic standard components from the automotive industry. A 500 kW Compressor test rig was built by SINTEF to test the 2-Stage configuration in superheated steam conditions. Compressor efficiency and system COP was calculated based on measurements from the test rig. Also, Compressor maps for the two Compressors was created. For the 1st Stage Compressor, the maximum isentropic efficiency was 67% and maximum pressure ratio 2.4. The second Stage yielded 77% and 2.0. The two-Stage configuration was able to produce 4.23 bar steam, from atmospheric inlet conditions. The system COP corresponded to 4.5 and a Carnot efficiency of 49.5 %. Keywords: Heat pumps, HTHP, Water R718, turbo Compressor, energy efficiency, steam productionacceptedVersio
Fengrui Sun - One of the best experts on this subject based on the ideXlab platform.
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optimum design of a subsonic axial flow Compressor Stage
Applied Energy, 2005Co-Authors: Lingen Chen, Fengrui SunAbstract:The design of an axial-flow Compressor Stage for subcritical Mach numbers has been formulated as a non-linear multi-objective mathematical programming problem with the objective of minimizing the aerodynamic losses and the weight of the Stage, while maximizing the Compressor's stall margin. Aerodynamic as well as mechanical constraints are considered in the optimization solution. The prediction model for estimating the performance characteristics, such as efficiency, weight and stall margin, of the Compressor Stage is presented. The present design optimization procedure can be applied to a multi-Stage Compressor.
Chasik Park - One of the best experts on this subject based on the ideXlab platform.
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performance evaluation of a two Stage compression heat pump system for district heating using waste energy
Energy, 2013Co-Authors: Ohkyung Kwon, Chasik ParkAbstract:The present study investigated a two-Stage compression heat pump system for district heating utilizing waste energy. An evaporator and condenser exhibit a large difference in temperature when hot water is produced for heating by a heat pump. With single-Stage compression, this causes a dramatic drop in the Compressor efficiency and lowers the system performance; so, in the present study, a two-Stage compression heat pump system comprising an intercooler and flash tank was designed, and the performance characteristics under various operating conditions were tested. When the heat source temperature was raised from 10 °C to 30 °C, the COP (coefficient of performance) was improved by up to 22.6%. As the superheating at the low-Stage Compressor was increased from 2 °C to 11 °C, the refrigerant flow rate and heating capacity decreased by as much as 7.6% and 2.2%, respectively, but there was no major impact on the temperature of the hot water produced nor on the system performance. Controlling the frequency of the high-Stage Compressor to control the intermediate pressure resulted in the ability to improve performance by as much as 5.2% under identical heat source conditions.
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performance evaluation of a two Stage co2 cycle with gas injection in the cooling mode operation
International Journal of Refrigeration-revue Internationale Du Froid, 2009Co-Authors: Changhyun Baek, Chasik ParkAbstract:Abstract The cooling performance and reliability of a transcritical CO2 cycle can be significantly improved by using a multi-Stage Compressor with gas injection because the CO2 cycle has a large pressure difference across a Compressor. The objective of this study is to investigate the performance and operating characteristics of a two-Stage CO2 cycle with gas injection. In this study, the performances of a two-Stage CO2 cycle with gas injection (called as “two-Stage gas injection cycle”) were measured as the amount of refrigerant charge, first- and second-Stage Compressor frequencies, and first- and second-Stage EEV openings were varied in the cooling mode operation. The cooling COP of the two-Stage gas injection cycle was maximally enhanced by 16.5% over that of the two-Stage non-injection cycle in the experiments. In addition, when the first- and second-Stage EEV openings were increased, the compression ratio decreased and this in turn, improved the cooling COP of the two-Stage gas injection cycle. However, when the first-Stage EEV opening was increased, the mass flow rate through the evaporator decreased, and this in turn, decreased the cooling capacity of the two-Stage gas injection cycle. Therefore, in the two-Stage gas injection cycle, an optimum control of both EEV openings is required.
