利用重力增压的新型有机工质热力发电循环

与水蒸气朗肯循环给水泵相比,有机朗肯循环工质泵存在技术难度大、效率低、易气蚀和单位功率成本高等问题。本文提出了一种利用重力增压的新型有机工质热力发电循环,冷凝器出口工质不经过泵而依靠重力增压,然后进入蒸发器气化。分别采用R113、R123和R245fa三种干工质分析了不同蒸发温度和冷凝温度下循环所需的重力增压高度。并基于泵的实验数据,比较了该热力循环与泵增压有机朗肯循环的性能。结果表明,相同工作温度下沸点和密度越高的工质所需的重力增压高度越小。在蒸发温度100℃和冷凝温度50℃时,若采用R113,新型循环所需的重力增压高度为22.2 m,热效率为8.1%,比泵增压循环效率高约0 8%。该重力增压循环显示了应用于热电联供领域的潜力。

A Novel Organic Thermodynamic Cycle on the Use of Gravity for Pressurization

Compared with water pump used in the steam Rankine cycle,pump for the organic Rankine cycle(ORC) has several disadvantages such as great difficulty in manufacture,low efficiency, easily-invited cavitation and high cost.A novel organic fluid thermodynamic cycle is proposed in this paper for heat to power conversion.Instead of pumping,the liquid from the condenser is pressurized due to gravity acting.Three kinds of dry fluids,R113,R123 and R245fa,are used to analyze the cycle performance on different evaporation and condensation conditions.The ORC pump is also tested. Based on the practical pumping efficiency,performances of the proposed thermodynamic cycle and the ORC cycle are compared.The results indicate that the height difference required for pressurization of working fluid in the gravity field is lower when high boiling point and liquid density fluid is used. On the condition of evaporation temperature of 100℃and condensation temperature of 50℃,the required height difference and the cycle power efficiency for R113 are 22.2m and 8.1%,respectively. And the efficiency of the proposed cycle is higher than that of pump-assisted ORC cycle by 0.8%.The proposed thermodynamic cycle underscores its potential for combined heat and power generation.