Investigation on the Performance of the Pump-Free Double Heat Source Ejector Refrigeration System with R1234yf

A pump is needed in an ejector refrigeration system,which makes the system high cost and complicated and hinders its application.A pump-free double heat source ejector refrigeration system using R1234yf as working fluid is proposed in which an injector driven by another heat source replaces the liquid circulating pump,making the system more affordable,simpler and more stable.The effect of different operation conditions on entrainment ratios and the influence of different factors on system performance are analyzed on the basis of mass,momentum and energy conservation equations.The influence degree of each factor on system performance is investigated by the orthogonal test method.The condenser temperature has the largest effect on system performance.The pressure drop in the suction chamber of gas-liquid injector has the least impact on system performance.The COP can reach about 0.35 under a certain working condition.The system can be driven by two different temperature heat sources with no electricity needed,and it is a good choice for places with abundant heat resources or lack of electricity.

Energy and Exergy Analysis of a Cooling/Power Cogeneration Ejector Refrigeration System

The organic Rankine cycle is introduced into the conventional ejector refrigeration(CER)system to establish the low-grade heat-driven cooling/power cogeneration ejector refrigeration(CPC-ER)system using the isobutane as the refrigerant.In comparison with the CER system where external power is consumed by the circulating pump,the power output from the CPC-ER system is more than the power consumption of its circulating pump so that a portion of net power is derived from the CPC-ER system.Based on the mathematical model of thermodynamics,energy and exergy analysis of the CPC-ER system is carried out and compared with the CER system.The results reveal that the equivalent coefficient of performance(COP)of the CPC-ER system is 41.14%to 71.30%higher than that of the CER system,and the exergy efficiency of the CPC-ER system is 1.32 to 1.49 times higher than that of the CER system.Both the power produced by the turbine and the total exergy output from the CPC-ER system approach the maximum,as the generating temperature in the generator is up to 80°C.The CPC-ER system has the higher energy utilization efficiency than the CER system,and it is suitable for the cooling and power-required places with low-grade thermal sources.

Experimental Investigation of the Ejector Refrigeration Cycle for Cascade System Application

Ejector refrigeration cycle(ERC)with advantages of simple structure and low cost holds great application potential in cascade/hybrid cycles to improve the overall system performance by removing or recovering the heat from the main cycle.In this paper,a theoretical and experimental investigation of the ERC as a part of a cascade system was carried out.The operating parameters were optimized.The experimental ERC test rig was designed,developed and investigated at high evaporating temperatures and wide ranges of operating conditions.The influence of operating conditions on the efficiency of the ejector and ERC was analyzed.Experimental results and analysis in this study can be helpful for the application and operating condition optimization of ERC in cascade/hybrid refrigeration systems.

Thermodynamic Analysis of a Mixed Refrigerant Ejector Refrigeration Cycle Operating with Two Vapor-liquid Separators

A mixed refrigerant ejector refrigeration cycle operating with two-stage vapor-liquid separators （MRERC2） is proposed to obtain refrigeration temperature at -40℃. The thermodynamic investigations on per- formance of MRERC2 using zeotropic mixture refrigerant R23/R134a are performed, and the comparisons of cycle performance between MRERC2 and MRERC1 CMRERC with one-stage vapor-liquid separator） are conducted. The results show that MRERC2 can achieve refrigeration temperature varying between -23.9℃ and -42.0℃ when ejector pressure ratio ranges from 1.6 to 2.3 at the generation temperature of 57.3-84.9℃. The parametric analysis indicates that increasing condensing temperature decreases coefficient of performance （COP） of MRERC2, and increasing ejector pressure ratio and mass fraction of the low boiling point component in the mixed refrigerant can improve COP of MRERC2. The MRERC2 shows its potential in utilizing low grade thermal energy as driving power to obtain low refrigeration temperature for the ejector refrigeration cycle.