基于TRNSYS的地埋管/换热水箱复合冷热源运行特性分析

OPERATING CHARACTERISTICS ANALYSIS OF COMPOSITE COLD AND HEAT SOURCES WITH COMBINATION OF GROUND HEAT EXCHANGER AND HEAT-EXCHANGE TANK BASED ON TRNSYS

针对地下工程水环热泵空调系统,提出采用地埋管与换热水箱并联的方式作为复合冷热源,可同时实现红外伪装和节能要求。为探讨该复合冷热源系统的运行换热特性,基于TRNSYS软件建立地埋管、换热水箱数理模型,首先对流体流速、进口温度等影响因素进行模拟分析,结果表明:在小流速情况下,增大流体流速可明显提高地埋管和换热水箱和换热效果;管内、外换热温差越大,换热器换热效果越好;在相同流速下,螺旋盘管的传热系数DN15>DN20>DN25>DN32。随后针对3种不同平、战负荷比工况,对复合冷热源的流量配比进行优化分析,结果表明:只要流量配比控制适当,复合冷热源可满足战时空调系统的供冷需求。复合冷热源之间存在最佳流量配比,β值越大,最佳流量配比的值越小,且不受环路流量与进口水温变化的影响,当β为1.0、1.5、2.0时,最佳流量配比依次为4/6、3/7、2/8。

In view of the water loop heat pump air conditioning system in underground engineering,it is proposed that the ground heat exchanger and heat-exchange tanks should be connected in parallel as its composite cold and heat sources,which can realize infrared camouflage and energy-saving at the same time.In order to study the operating characteristics of the composite cold and heat sources system,the mathematical model of buried pipe and heat-exchange tank is set up based on TRNSYS software.First,the influence factors such as flow velocity and inlet temperature and so on are simulated and analyzed.It concludes that increasing flow velocity can obviously improve the heat transfer effect both of heat-exchange tank and buried pipe under the condition of small flow velocity.And the greater heat transfer temperature difference is,the better the heat transfer effect of the heat exchanger is.At the same flow rate,the heat transfer coefficient of the spiral coil is DN15>DN20>DN25>DN32.Afterwards,the flow ratio of the composite cold and heat sources is optimized and analyzed for three different load ratios of wartime to peacetime.Results show that the composite cold and heat sources can meet the demand for cooling in war time as long as the flow ratio is properly controlled.The flow ratio between the composite cold and heat sources has the optimal value.And it is not affected by the flow of the loop and inlet temperature.The bigger the β is,the smaller the optimal flow ratio is.When the β is 1.0,1.5 and 2.0,the optimal flow rates are 4/6,3/7 and 2/8,respectively.