Poljak Igor, Orović Josip, Mrzljak Vedran, Bernečić Dean
Maritime Department, University of Zadar, Mihovila Pavlinovića 1, 23000 Zadar, Croatia.
Faculty of Engineering, University of Rijeka, Vukovarska 58, 51000 Rijeka, Croatia.
Entropy (Basel). 2020 Jan 17;22(1):115. doi: 10.3390/e22010115.
Data from a two-stage axial vapor cryogenic compressor on the dual-fuel diesel-electric (DFDE) liquefied natural gas (LNG) carrier were measured and analyzed to investigate compressor energy and exergy efficiency in real exploitation conditions. The running parameters of the two-stage compressor were collected while changing the main propeller shafts rpm. As the compressor supply of vaporized gas to the main engines increases, so does the load and rpm in propulsion electric motors, and vice versa. The results show that when the main engine load varied from 46 to 56 rpm at main propulsion shafts increased mass flow rate of vaporized LNG at a two-stage compressor has an influence on compressor performance. Compressor average energy efficiency is around 50%, while the exergy efficiency of the compressor is significantly lower in all measured ranges and on average is around 34%. The change in the ambient temperature from 0 to 50 °C also influences the compressor's exergy efficiency. Higher exergy efficiency is achieved at lower ambient temperatures. As temperature increases, overall compressor exergy efficiency decreases by about 7% on average over the whole analyzed range. The proposed new concept of energy-saving and increasing the compressor efficiency based on pre-cooling of the compressor second stage is also analyzed. The temperature at the second stage was varied in the range from 0 to -50 °C, which results in power savings up to 26 kW for optimal running regimes.
对双燃料柴油电力（DFDE）液化天然气（LNG）运输船上的两级轴向蒸汽低温压缩机的数据进行了测量和分析，以研究实际运行条件下压缩机的能量和火用效率。在改变主传动轴转速时，收集了两级压缩机的运行参数。随着压缩机向主机供应的汽化气体增加，推进电动机的负载和转速也会增加，反之亦然。结果表明，当主推进轴上的主机负载从46转/分钟变化到56转/分钟时，两级压缩机处汽化LNG质量流量的增加会对压缩机性能产生影响。压缩机的平均能量效率约为50%，而在所有测量范围内，压缩机的火用效率显著较低，平均约为34%。环境温度从0℃到50℃的变化也会影响压缩机的火用效率。在较低的环境温度下可实现更高的火用效率。随着温度升高，在整个分析范围内，压缩机的整体火用效率平均下降约7%。还分析了基于压缩机第二级预冷的节能和提高压缩机效率的新概念。第二级的温度在0℃到-50℃范围内变化，在最佳运行状态下可节省高达26千瓦的功率。
