Efficiency and effectiveness enhancement of an intercooler of two‐stage air compressor by low‐cost Al2O3/water nanofluids

The present study was aimed to utilize low‐cost alumina (Al₂O₃) nanoparticles for improving the heat transfer behavior in an intercooler of two‐stage air compressor. Experimental investigation was carried out with three different volume concentrations of 0.5%, 0.75%, and 1.0% Al₂O₃/water nanofluids to assess the performance of the intercooler, that is, counterflow heat exchanger at different loads. Thermal properties such as thermal conductivity and overall heat transfer coefficient of nanofluid increased substantially with increasing concentration of Al₂O₃ nanoparticles. Specific heat capacity of nanofluids were lower than base water. The intercooler performance parameters such as effectiveness and efficiency improved appreciably with the employment of nanofluid. The efficiency increased by about 6.1% with maximum concentration of nanofluid, that is, 1% at 3‐bar compressor load. It is concluded from the study that high concentration of Al₂O₃ nanoparticles dispersion in water would offer better heat transfer performance of the intercooler.     

基于热平衡台架试验的高强化柴油机冷却系统研究

通过某型高强化柴油机全工况热平衡台架试验，分析了柴油机本体出水温度对柴油机本体散热及中冷器散热规律的影响；指出高强化柴油机智能化控制冷却系统应采用高、低温双循环回路方案，其中高温回路主要用于冷却柴油机本体，而低温回路应以控制增压空气温度为目标对中冷器冷却强度进行独立调节，从而有效地改善高强化柴油机的综合性能。     

Thermodynamic studies of a HAT cycle and its components

The electric power grid contains more and more renewable power production such as wind and solar power. The use of renewable power sources increases the fluctuations in the power grid which increase the demand for highly efficient, fast-starting power-producing units that can cope with sudden production losses. One of the more innovative power plant cycles, that have the potential of competing with conventional combined power plants in efficiency but has a higher availability and faster start up time, is the Evaporative Gas Turbine (EvGT) or Humid Air Turbine (HAT). A thermodynamic evaluation of different HAT cycle layouts has been done in this paper. Each layout is evaluated separately which makes it possible to study different components individual contribution to the efficiency and specific power. The thermodynamic evaluation also shows that it is important to look at different cool-flow extracting positions. The effect of water temperature entering the cycle, called make-up water, and where it is introduced into the cycle has been evaluated. The make-up water temperature also affects the optimal pressure level for intercooling and it is shown that an optimal position can be decided considering design parameters of the compressor and the water circuit.     

跨临界CO_2双级压缩制冷循环的热力学分析与比较

对带中间冷却器的双级压缩制冷(TCEI)循环和带闪发器的双级压缩制冷(TCFI)循环进行了热力学分析与比较。结果表明:TCFI循环的最佳中间压力和最佳排气压力低于TCEI循环。在常规空调工况下,TCFI循环的COP高于TCEI循环。在蒸发温度从-10℃变化到10℃时,TCFI循环和TCEI循环的COP相对基本循环平均提高幅度分别为32.3%和18.7%。     

往复活塞式压缩机冷却系统的设计及进展

为保证往复活塞式压缩机的运行可靠性和经济性,必须通过冷却系统对其进行良好的冷却。针对不同类型的压缩机,对风冷式压缩机和水冷式压缩机的冷却系统的组成、特点、设计原则分别进行了阐述。进而对压缩机冷却系统在冷却器等方面的研究和改进的进展情况作了介绍。     

增压器和中冷器联合性能试验台

增压器和中冷器是柴油机增压系统的重要部件 ,其性能的优劣直接影响柴油机的经济性、动力性及可靠性。目前 ,我国机务部门已经实现了增压器的集中修理 ,并有完备的性能试验设备 ,但对中冷器的性能试验还缺乏必要的设备 ,这使装车运用的中冷器质量难以得到保证。为此 ,提出了建造增压器、中冷器联合试验台方案 ,它具有投资少 ,试验费用低 ,维修保养方便等优点。     

改性EPDM中冷器出气胶管的开发及应用

介绍了汽车柴油发动机中冷器出气胶管的特点,比较了硅橡胶与三元乙丙橡胶的性能特征。通过产品结构设计、材料配方和成型工艺研究,开发能够代替硅胶管的低成本的改性EPDM中冷器出气胶管。经过对研制胶管的全面性能测试、装车路试认定、装配工艺和使用情况评价,新型胶管完全满足产品的技术性能和使用要求,其开发应用能够大幅度降低采购成本,具有显著的经济效益。     

冷却系统热流量分配计算与试验对比分析

根据能量守恒原理和多项式拟合的方法对冷却系统内冷却液从发动机水套、中冷器以及机油热交换器中带走的热流量进行了数值仿真计算,并与试验值进行对比,计算结果与试验值符合较好且相对误差小于10%;同时计算得到了发动机不同工况下,冷却液从发动机水套、中冷器带走热流量随发动机转速、负荷的变化关系.     

工艺空气压缩机异常喘振的原因分析及对策

对工艺空气压缩机组发生异常喘振的原因进行了分析,针对可能存在的原因采取了一系列措施,消除了该机组的不稳定工况。     

ICR进展及关键技术

ＩＣＲ燃气轮机继承了简单循环燃气轮机的一系列优点,且具有优良的变工况性能。ＷＲ－２１代表了ＩＣＲ的最先进水平。本文简述了ＷＲ－２１燃气机的最新进展,对中冷器、回热器、箱装体、数字控制系统等重要部件的关键技术进行了分析。