Experimental and Theoretical Investigation of a Hybrid Compressor and Ejector Refrigeration System for Automotive Air Conditioning Application

In this research, performance of a hybrid compressor and ejector refrigeration system for automotive air conditioning application was investigated theoretically and experimentally. Mathematical modeling integrated the 1-dimensional analysis of ejector with the thermodynamic analysis of the hybrid compressor and ejector refrigeration system via EES (Engineering Equation Solver) software was proposed. Also an experimental rig of the hybrid compressor and ejector refrigeration system for automotive air conditioning application was built. This hybrid system has a rated cooling capacity of 3.5 kW. Refrigerant R134a and R141b were used for mechanical vapor compression sub system and the ejector sub system, respectively. The operating conditions are chosen accordingly as, generator temperature between 100 °C and 120 °C, condenser temperature between 30 °C and 40 °C, and evaporator temperature between 0 °C and 10 °C. Theoretical results of the ejector’s entrainment ratio (Rm) and COP of the system with variations on operating conditions were compared with the experiment values. From the results, mathematical modeling seems to provide error in COP prediction up to 15.5% when compared with experimental values. Fortunately, modification of the mathematical modeling by applying the computational fluid dynamics (CFD) technique provides less error about 5.5%. It’s also found that the COP of the hybrid system can be increased by 10-20% compared to a simple stage ejector refrigeration cycle (EJC). Moreover, estimated power consumption of the automotive air conditioning system can be approximately reduced 20% under the conventional vapor compression cycle.In this research, performance of a hybrid compressor and ejector refrigeration system for automotive air conditioning application was investigated theoretically and experimentally. Mathematical modeling integrated the 1-dimensional analysis of ejector with the thermodynamic analysis of the hybrid compressor and ejector refrigeration system via EES (Engineering Equation Solver) software was proposed. Also an experimental rig of the hybrid compressor and ejector refrigeration system for automotive air conditioning application was built. This hybrid system has a rated cooling capacity of 3.5 kW. Refrigerant R134a and R141b were used for mechanical vapor compression sub system and the ejector sub system, respectively. The operating conditions are chosen accordingly as, generator temperature between 100°C and 120°C, condenser temperature between 30°C and 40°C, and evaporator temperature between 0°C and 10°C. Theoretical results of the ejector's entrainment ratio (Rm) and COP of the system with variations on operating conditions were compared with the experiment values. From the results, mathematical modeling seems to provide error in COP prediction up to 15.5% when compared with experimental values. Fortunately, modification of the mathematical modeling by applying the computational fluid dynamics (CFD) technique provides less error about 5.5%. It's also found that the COP of the hybrid system can be increased by 10 - 20% compared to a simple stage ejector refrigeration cycle (EJC). Moreover, estimated power consumption of the automotive air conditioning system can be approximately reduced 20% under the conventional vapor compression cycle

COP Prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning

This paper presents the COP prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning. Using computational fluid dynamics (CFD) technique, the performance of an ejector was analyzed in term of the entrainment ratio (Rm) and critical back pressure (CBP). The results from this study were compared with a previous study of combined ejector refrigeration system for automotive air conditioning application [1] which the entrainment ratio (Rm) were predicted from one-dimensional (1-D) equation. The performance of an ejector (Rm and CBP) from CFD and onedimensional method were analyzed and used as database for a mathematical modeling. In order to predict the COP of the combined system, a set of mathematical equations was developed using EES. The operating conditions are chosen accordingly as, intercooler temperature between 15 ๐ C and 25 ๐ C, condenser temperature equal to 35 ๐ C and evaporator temperature equal to 5 ๐ C. However, when generator temperatures are 80 ๐ C, 85 ๐ C and 90 ๐ C, the results showed average relative errors of the COP of an ejector refrigeration cycle (COPej), between CFD and 1-D are 44.64%, 50.47% and 59.68% respectively, and between CFD and 1-D NEW are 1.54%, 0.08% and 6.49% respectively

การจำลองพฤติกรรมการเผาไหม้ของเตาประหยัดแก๊ส s-10 ด้วยวิธีพลศาสตร์ของไหลเชิงคำนวณ

วารสารวิชาการและวิจัย มทร.พระนคร, ปีที่ 14, ฉบับที่ 1 (ม.ค.-มิ.ย. 2563), หน้า 165-176The objective of this research is to study the combustion behavior of a gas-saving burner S-10 using computational fluid dynamics (CFD). The simulation model was created using Fluent 6.3 in 3D-model of the same size of the burner. LPG pressure of 4 psi was released for this study. The combustion behavior was shown in temperature contour and velocity vector. The CFD results were verified by measuring the temperature around the burner head with a vessel. From the study, it was found that the CFD’s results of flow velocity and combustion temperature distributions were validated with the experimental values. The CFD’s result errors were less than 10.35% and 11.87%, comparing with the velocity and temperature measurement, respectively. The fluid flow and combustion behaviors can be described by this CFD model. Moreover, the CFD model of the gas-saving burner S-10 can be applied to improve the thermal efficiency of the burner in the future.Rajamangala University of Technology Phra Nakho