Authors

Abstract

A drying system powered by heat recovered from the exhaust gas of combine harvester using the gravity heat pipe heat exchanger (HPHE) was proposed to improve the fuel efficient of combine harvester. The full-load characteristics of diesel engine were obtained through bench test. The constant heat flux method was used to calculate the heat transfer performances of every heat pipe and then the influence of inlet air parameters at the cold-side of HPHE on the heat transfer process were analyzed by computational fluid dynamics (CFD) simulation under the rated condition (RC) and maximum torque condition (MTC). The results show: for both working conditions, the inlet air velocity has greater effect on the heat transfer performances than the inlet air temperature and the outlet air temperatures are all suitable for the grain drying; the overall heat transfer coefficient of HPHE is higher under RC compared with MTC.

Abstract in Chinese

为了提升联合收割机发动机能源利用率，提出一种采用重力热管换热器的柴油机尾气余热回收的联合收割机谷物干燥系统。通过柴油机台架试验获取某型号联合收割机柴油机包含排气特性在内的外特性。针对该柴油机常用的额定工况和最大转矩工况，通过将热管假定为定热源，采用定热流密度法获取的每一根热管的传热性能参数，然后将各热管的传热性能参数代入到CFD仿真模型，计算出了重力热管换热器冷侧的空气入口温度和入口流速对换热过程的影响。研究结果表明：在两种柴油机工况下，进口风速对换热过程的影响要远大于进口风温；虽然柴油机在最大转矩工况工作时，换热器冷侧空气出口温度变化范围比额定工况窄，但是该风温也能够满足谷物干燥的需求；相比于最大转矩工况，当柴油机工作于额定工况时热管换热器能够回收更多的排气余热能且总传热效率也更高。