Study on Power System Using High Pressure Air Generator for Saving Energy

提出了一种以高压空气为工质的混合动力系统，并对其性能和效率进行了研究。该系统主要由柴油机压缩机、高压气箱和空气膨胀机组成。柴油压缩机利用同一气缸燃烧提供的能量，通过压缩产生高压空气。空气被转移到空气罐中，储存在那里，并被输送到膨胀机，根据电力需求获得功率输出。能量分析和(火用)分析结果表明，该系统具有与布雷顿循环相同的热效率，在满足不同输出功率的情况下，需要对压比和截止率等参数进行优化，以提高(火用)效率。测试结果表明，输出功率不能在较宽的范围内完全控制。通过对阀门形状的改进，有效地扩大了可控输出范围。此外，排气口时间面积的增加将提供更好的热效率和更宽的功率范围。

A hybrid power system using high-pressure air as working fluid has been proposed and its pefformance and efficiency were studied. This system is mainly composed of a diesel compressor, a high-pressure air tank and an air expander. The diesel compressor generates high-pressure air by compression using energy supplied by combustion in the same cylinder. The Air is transferred into the air tank, stored there and is delivered to the expander to obtain the power output according to the power demand. This system is supposed to have some advantages, that is, reduction in transmission loss using variable output air expander, improvement in engine thermal efficiency due to the limitation of its speed and output and energy saving due to brake energy recovery.The results of energy and exergy analysis show that the ideal cycle of this system has the same thermal efficiency as Brayton cycle and that some parameters such as pressure ratio and cut-off ratio should be optimized for increasing exergy efficiency when various power output is required.The prototype of the air expander was designed and constructed. The test results show that the output power could not be fully controlled over the wide range. The modification of valve shape proved to be effective to extend the controllable output range. In addition the increase in exhaust port time area will give better thermal efficiency and broader power range.