On the study of an energy-efficient greenhouse for heating, cooling and dehumidification applications

An analytical model, based on basic heat-transfer processes within a greenhouse, was used to study the performance of heat pump to meet the heating and dehumidification requirements in a greenhouse. Performance parameters of the heat pump, namely the Coefficient of Performance (COP) and the Specific Energy Consumption (SEC) of the heat pump were determined, along with the condenser and evaporator capacity ratings required to provide the necessary thermal conditioning to a model-sized greenhouse. Based on a typical weather pattern in Bangkok, the performance of the heat pump to maintain the greenhouse air at a day temperature of 27 °C and night temperature of 18 °C with a relative humidity of 40% spans 1.2–4.0 and 1000–16,000 kJ/kg for COP and SEC, respectively.     

R141b气液两相喷射器性能研究

考虑实际流体性质、混合室阻力和喉部激波现象,采用等压混合模型,根据质量守恒、动量守恒和能量守恒建立中心进气两相喷射器一维模型。以R141b为工质,研究在不同入口参数和混合室截面积变化比(混合室喉部截面积与混合室入口截面积之比)下喷射器的升压特性以及入口参数和混合室截面积变化比对喷射器出口压力和喷射系数的影响。结果表明:在一定工况下,入口主蒸汽压力每增加0.5 MPa,喷射器出口压力提高约0.002 MPa;入口引射液体压力每增加0.1 MPa,出口压力约升高0.6 MPa。相对于入口主蒸汽参数的变化,入口引射液体参数变化对喷射器的升压特性影响更大。另外,随着混合室截面变化比的增大,升压效果下降。在入口引射液体参数为0.1 MPa/299 K和0.2 MPa/321 K的条件下,混合室截面积比分别增至0.6和0.4时,出口处蒸汽不能完全凝结。研究结果适用于大部分工质,为喷射器的设计和运行提供理论指导。     

基于多元线性回归直膨式太阳能热泵性能预测

针对直膨式太阳能热泵(DX-SAHP)系统运行工况复杂、系统热力性能预测较为困难的问题,提出基于多元线性回归算法的系统性能预测模型.在对环境参数和运行参数与系统性能系数(COP)之间相关性分析的基础上,利用Python语言编写了具有自学习能力的训练模型程序,分别将春秋季、夏季和冬季工况下的实验数据作为模型样本训练数据,...