The performance of the jet refrigeration cycle refers to the entrainment ratio and the critical condenser pressure of an ejector. The only way to increase the secondary flow simultaneously with the ejector discharge pressure is to increase the secondary pressure. Unfortunately, for the conventional jet refrigerator, increasing evaporator temperature (refrigeration effect) is the must. In 1990, Sokolov and Hearshgal, introduced new configurations of efficient uses of the mechanical power in order to enhance the secondary pressure without disturbing the refrigeration temperature, which are: (1) the booster assisted ejector cycle (Fig. 11a) and (2) the hybrid vapour compression-jet cycle (Fig. 11b). Their simulated results show that the compression enhanced ejector can significantly improve the system performance. Please note that, the power required by the booster is much greater than that required by the circulation pump and cannot be omitted in the evaluation of system performance. The booster assisted ejector cycle is very similar to the conventional ejector cycle. The low-pressure ratio mechanical-driven compressor is placed between the evaporator outlet and ejector suction line. Therefore, the ejector can sense a higher suction pressure, which provides an increase of its performance. Anyway, in practice, the entrainment of oil droplets from the booster may adversely affect the smooth and clean operation of the ejector. The reduced compression ratio of ejector allows the application of low temperature refrigeration to the solar driven jet refrigeration system. The hybrid compression-jet refrigeration system consists of a conventional compression and ejector sub-cycles with heat exchanger as an interface between them. According to its configuration, pressure ratios across the ejector and the compressor are maintained at low level. The heat load is transferred from an evaporator to a heat exchanger and then compressed and rejected to the surrounding at a condenser. In other words, the ejector sub-cycle was used as the heat rejection system. If a single refrigerant is used, the heat exchanger is replaced by the mixing chamber and combined both heat and mass transfer processes. The concepts and design procedures of the systemwere explained in, while the description of the constructed multi-ejector R114 machine and its experimental data were given in. the mathematical simulation (effect of operating condition) of a constructed machine and a machine with the utilization of solar energy were made respectively. However, R114 was found to be harmful to the environment and be prohibited, Da-Wen Sun conducted the mathematical simulation of an environmental friendly solar system. Steam and R134-a were used as the refrigerant in an ejector and a compression sub-cycle, respectively. The simulated results showed that the COP of the system could be improved up to 50% compared to the conventional vapour compression system. The analysis of maximum possible COP of a solar powered hybrid compression-jet refrigerator, in term of Carnot efficiency, was provided in. It is obvious that the booster and the vapour compression cycle can provide higher thermal efficiency to the jet refrigeration system. On the other hand, either