Refrigeration and air conditioning systems consume about 17% of the world-wide electricity and their conventional refrigerants cause ozone depletion and global warming. In this study a novel thermo-mechanical refrigeration (TMR) system is developed and analyzed that is powered, instead of electricity, by thermal energy from waste heat or renewable sources in the ultra-low temperature range of 60–100 °C. A novel isobaric expander-compressor unit (ECU) is designed and combined with vapor compression refrigeration cycle to constitute the TMR system. The technological solutions (mainly towards simplification of the design) are crucial components of the study novelty. The suitable refrigerants for the system are systematically investigated, analyzed and selected from a list of 43 refrigerants. Nine fluids for the power loop (the isobaric expansion cycle) and nine fluids for the cooling loop (the thermal refrigeration cycle) were selected and compared based on their mode of operation (subcritical and supercritical), environmental effects and safety class. It is found that the HFO refrigerants such as R1234yf and R1234ze have acceptable performance with no ODP and very low GWP. Natural refrigerants R717 (ammonia) has the best performance in subcritical mode with toxicity as the main drawback. At heat source temperatures less than 85 °C, the system operation in subcritical mode is more efficient and more compact than in the supercritical mode. Thorough analysis and recommendations are made for the size of the ECU in terms of the diameters of the expander and the compressor.

制冷和空调系统消耗全球约17％的电力，其常规制冷剂导致臭氧消耗和全球变暖。在这项研究中，开发并分析了一种新型的热机械制冷（TMR）系统，该系统由60-100°C的超低温范围内的废热或可再生资源产生的热能代替电能。设计了一种新型的等压膨胀机-压缩​​机单元（ECU），并与蒸气压缩制冷循环组合构成了TMR系统。技术解决方案（主要是简化设计）是研究新颖性的关键组成部分。从43种制冷剂清单中系统地研究，分析和选择了适合该系统的制冷剂。根据操作方式（亚临界和超临界），环境影响和安全等级，选择了九种用于动力回路（等压膨胀循环）的流体和九种用于冷却回路（热制冷循环）的流体，并进行了比较。发现诸如R1234yf和R1234ze之类的HFO制冷剂具有可接受的性能，没有ODP和非常低的GWP。天然制冷剂R717（氨）在亚临界模式下具有最佳性能，其主要缺点是毒性。在热源温度低于85°C时，与超临界模式相比，亚临界模式下的系统运行效率更高，结构更紧凑。根据膨胀机和压缩机的直径，对ECU的尺寸进行了详尽的分析和建议。