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首页> 外文会议>ISES solar world congress >DEVELOPMENT OF A PERFORMANCE CALCULATION PROGRAM FOR SOLAR DOMESTIC HOT WATER SYSTEMS WITH IMPROVED PREDICTION OF THERMAL STRATIFICATION
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DEVELOPMENT OF A PERFORMANCE CALCULATION PROGRAM FOR SOLAR DOMESTIC HOT WATER SYSTEMS WITH IMPROVED PREDICTION OF THERMAL STRATIFICATION

机译：改进了热分层预测的太阳能家用热水系统性能计算程序的开发

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The transient fluid flow and heat transfer in a hot water tank during cooling caused by standby heat loss were investigated by computational fluid dynamics (CFD) calculations and by thermal measurements in previous investigation. It is elucidated how thermal stratification in the tank is influenced by the natural convection and how the heat loss from the tank sides will be distributed at different levels of the tank at different thermal conditions. A heat loss removal factor is introduced to characterize the effect of the buoyancy driven flow on exchange of heat loss between tank layers by natural convection. Based on results of the CFD calculations, a generalized equation of the heat loss removal factor is obtained by regression which calculates the heat loss removal factor for a given temperature gradient in the tank. The equation takes into account the influences of tank volume, height to diameter ratio, tank insulation, thickness and material property of the tank wall and initial thermal conditions of the tank. The equation is validated for a tank volume in the range of 150 1 and 500 1 and a height to diameter ratio of 1-5. The equation is implemented in a simulation program for a solar domestic hot water (SDHW) system with a hot water tank charged by a built-in heat exchanger spiral. The program can calculate thermal performance of a SDHW system. Thermal performance calculated by the program will be compared to the measurements. The investigations elucidate accuracy and reliability of the program for calculation of temperatures and thermal performance of a solar domestic hot water system.
机译：通过计算流体力学（CFD）计算和以前的研究中的热测量方法，研究了由待机热量损失引起的冷却期间热水箱中瞬态流体流动和传热问题。阐明了自然对流如何影响储罐中的热分层，以及在不同的热工况下，储罐侧面的热量损失将如何分布在储罐的不同高度上。引入了热损失去除因子来表征浮力驱动流对通过自然对流进行的罐层之间热损失交换的影响。根据CFD计算的结果，通过回归获得散热损失因子的通用方程式，该方程可计算罐中给定温度梯度下的散热损失因子。该方程式考虑了储罐容积，高度与直径之比，储罐隔热，储罐壁的厚度和材料特性以及储罐的初始热工状况的影响。该方程式在罐容积为150 1至500 1且高度与直径之比为1-5的情况下得到验证。该方程式在带有热水箱的太阳能家用热水（SDHW）系统的仿真程序中实现，该热水箱由内置的热交换器螺旋管填充。该程序可以计算SDHW系统的热性能。将程序计算出的热性能与测量结果进行比较。这些调查阐明了用于计算家用太阳能热水系统的温度和热性能的程序的准确性和可靠性。

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