Mechanical Engineering Department, College of Engineering, Taif University, Taif, Saudi Arabia.
J Adv Res. 2016 Sep;7(5):651-60. doi: 10.1016/j.jare.2016.06.006. Epub 2016 Jun 30.
The potential use of many common hydrofluorocarbons and hydrocarbons as well as new hydrofluoroolefins, i.e. R1234yf and R1234ze(E) working fluids for a combined organic Rankine cycle and vapor compression refrigeration (ORC-VCR) system activated by low-grade thermal energy is evaluated. The basic ORC operates between 80 and 40 °C typical for low-grade thermal energy power plants while the basic VCR cycle operates between 5 and 40 °C. The system performance is characterized by the overall system coefficient of performance (COPS) and the total mass flow rate of the working fluid for each kW cooling capacity ([Formula: see text]). The effects of different working parameters such as the evaporator, condenser, and boiler temperatures on the system performance are examined. The results illustrate that the maximum COPS values are attained using the highest boiling candidates with overhanging T-s diagram, i.e. R245fa and R600, while R600 has the lowest [Formula: see text] under the considered operating conditions. Among the proposed candidates, R600 is the best candidate for the ORC-VCR system from the perspectives of environmental issues and system performance. Nevertheless, its flammability should attract enough attention. The maximum COPS using R600 is found to reach up to 0.718 at a condenser temperature of 30 °C and the basic values for the remaining parameters.
评估了许多常见的氢氟碳化合物和碳氢化合物以及新型氢氟烯烃（即 R1234yf 和 R1234ze(E)）作为工质在由低品位热能驱动的有机朗肯循环和蒸汽压缩制冷（ORC-VCR）组合系统中的潜在用途。基本的 ORC 在 80 到 40°C 之间运行，这是低品位热能发电厂的典型温度，而基本的 VCR 循环在 5 到 40°C 之间运行。系统性能由总系统性能系数（COPS）和每个千瓦冷却能力的工作流体总质量流量来表征([Formula: see text])。研究了不同工作参数（如蒸发器、冷凝器和锅炉温度）对系统性能的影响。结果表明，使用具有悬垂 T-s 图的最高沸点候选物（即 R245fa 和 R600）可获得最大的 COPS 值，而在考虑的运行条件下，R600 的[Formula: see text]最低。在所提出的候选物中，从环境问题和系统性能的角度来看，R600 是 ORC-VCR 系统的最佳候选物。然而，其可燃性应引起足够的重视。在冷凝器温度为 30°C 和其余参数的基本值下，使用 R600 可达到最大 COPS 值 0.718。
