Energy and exergy performance evaluation of an ejector enhanced Joule-Thomson cycle with binary mixtures

In this paper, a modified ejector enhanced Joule-Thomson cycle (EJTC) with binary mixture R1150/R600a was proposed for −80 °C low temperature freezer applications. The ejector was utilized as an expansion device to improve the cycle performance by recovering the expansion work. Moreover, the two-phase refrigerant from the ejector would be fully involved in the recuperative process of this cycle because there was no need for any vapor–liquid separator. Therefore, the proposed cycle was beneficial to the lubricant oil return for the compressor. The thermodynamic modeling developed by energy and exergy equations was employed to investigate the cycle behaviors of EJTC and compared them with the basic Joule-Thomson cycle (BJTC). The results indicated that the COP and volumetric refrigeration capacity q_ev of EJTC were improved by 32.2% and 47.8% compared with those of BJTC at the typical operating condition. Especially, the EJTC achieved the higher performances improvement in COPs and q_ev under the lower evaporating temperature. And the highest COPs and q_ev could be obtained at the optimal R1150 mass fraction of 0.4. The theoretical results show that the proposed cycle has great potential advantages for practical applications in the low temperature freezers.