蓄热水箱对太阳能-水源热泵系统性能特性的影响分析及实验研究

为了分析蓄热水箱对太阳能-水源热泵系统性能特性的影响,提高系统的运行效率,提出太阳能-水源热泵复合地板辐射采暖系统(SWHP-RFH)的实时动态数学模型及系统控制策略并在北京科技大学搭建SWHP-RFH实验台。对北京市2009年12月15日测试数据与仿真实验进行对比分析。结果表明:利用水箱分层原理对系统进行运行控制时,系统的COP从3.315升高到3.558。水箱分层研究可为太阳能-水源热泵复合地板辐射采暖系统的优化设计提供重要的指导作用。     

太阳能地面采暖系统蓄热水箱容积分析

通过分析太阳能采暖系统所需蓄热鼍与建筑热负荷、太阳能集热量日变化规律之间的关系,得出太阳能采暖系统所需蓄热水箱容积的理论算式.根据拉萨、银川、西宁、西安等地的太阳辐射强度及建筑热负荷的日变化规律,模拟得出系统所需蓄热量变化规律;并对各种蓄热温差下对应的蓄热水箱容积进行了模拟分析,结果表明:太阳能采暖系统所需蓄热量随太阳集热器的集热量与建筑热负荷之间的差值增大而增加;蓄热水箱容积随蓄热温差增大而减小,当蓄热水温达到80℃时,在各种地面采暖系统取水温度下,单位集热器面积所需蓄热水箱容积趋于相等.     

太阳能蓄热水箱的温度分层研究

太阳能蓄热水箱中形成一定程度上的温度分层有助于提高集热效率,降低传热损失。本文建立了水箱温度分层的理论分析模型,并利用cFD软件模拟了水箱中的流动、换热、温度分层过程,分析了多个因素对温度分层效果的影响,并与实验结果进行了分析和比较,两者较吻合。本文研究方法和结果为进一步优化设计太阳能蓄热水箱提供了依据。     

太阳能蓄热分层水箱数值模拟优化分析

蓄热水箱能够存储和调配能量。将蓄热水箱应用到太阳能热水系统中,可以弥补太阳能的不稳定性和不连续性,有效地提高太阳能热水系统的热利用率。文章基于小型太阳能热水系统,建立蓄热水箱物理模型,应用Fluent软件模拟分析了各个工况下蓄热水箱的温度分层情况,从而寻求较优的温度分层。分析结果表明:当热水入口质量流量小于2.8 kg/s时,蓄热水箱的温度分层比较明显;当热水入口质量流量大于2.8 kg/s时,随着热水入口质量流量逐渐增大,蓄热水箱温度分层越来越不明显;热水入口温度与水箱初始温度对于蓄热水箱温度分层影响不大;当热水入口质量流量为2.8 kg/s时,存在最佳热水入口直径(9 mm),此时蓄热水箱冷、热水不发生混合,蓄热水箱的热利用率较高。     

新型稳流器蓄热水箱温度分层现象的研究

该文设计了一个由顶部稳流器、底部稳流器、2个侧面稳流器以及上部挡水板和下部挡水板组成的蓄热水箱。为了研究蓄热水箱运行时的温度分层效果,用Gambit建立蓄热水箱模型,并且用Fluent分别模拟热泵机组蓄热水箱供暖模式和热泵机组蓄热水箱既蓄热又供暖模式。模拟结果表明,蓄热水箱供热模式可满足持续供热时间为360 min,并且出水口温度始终高于313 K;而对比模型在相同工况下仅能提供60 min的热水。在温度分层方面,运行480 min后,蓄热水箱上部与中部的最终平均温差为6.8 K,蓄热水箱中部与下部的平均温差为4.6 K。     

基于插栓流模型的太阳能供热系统的研究

采用蓄热水箱的多节点模型,对典型太阳能供热系统进行全年逐时模拟计算.计算数据表明,相比于完全混合的蓄热水箱,水箱温度分层可较大幅度提高太阳能集热器的平均效率和太阳能保证率.同时还分析了不同集热器类型、供水温度、供回水温差等条件下.蓄热水箱温度分层对太阳供热系统性能提高程度的影响.     

太阳能相变蓄热复合土壤源热泵系统的研究

叙述了以太阳能相变蓄热装置蓄热,且与蒸发器进口处换热的辅助热泵系统,用20号蓄热专用石蜡,通过板式换热器与蒸发器进水管进行热量传递的实验。指出,利用太阳能集热器在白天升高蒸发器侧的温度提高热泵效率,利用储存在蓄热装置中的热量夜晚可对蒸发器的进水增温,以此实现太阳能相变蓄热装置与复合土壤源热泵系统的良好结合,提高整个系统的供热效率。     

主动太阳能采暖供水管流量规律研究

通过对集热器有效集热量、建筑热负荷、蓄热系统蓄热量、蓄热水箱损失以及蓄热水箱温度的理论分析,建立了太阳能采暖供水管流量数学模型,且分别在不同太阳辐射强度与不同建筑热负荷波动规律下进行模拟分析,得出蓄热水箱温度变化规律以及各种情况下采暖供水管流量变化规律.结果表明:蓄热水箱温度受太阳辐射强度波动规律影响较大,受建筑热负荷波动规律影响较小,其中蓄热水箱温度基本在30～70℃之间;太阳辐射强度相同,建筑热负荷越大所需采暖管流量也越大,流量最大、最小值分别可达到0.810、0.008kg/s;随着太阳辐射强度波动规律的增大,采暖管流量波动规律亦相应增大.     

太阳能供暖二级水箱变容积蓄热系统能量及?分析

太阳能供暖系统中的固定容积单水箱蓄热系统,在太阳能波动供给和建筑热负荷波动需求之间存在不匹配及灵活性不足的问题。为更高效地利用太阳能,本文对二级水箱温度分层变容积蓄热太阳能供暖系统建立了MATLAB数学模型,包括集热循环、充热循环、取热循环和供热循环四部分及相应的控制策略,并运用Trnsys进行了模型验证。提出了在某时间段内,实际参与充热、取热或同时充热与取热的水箱体积为有效蓄热体积的概念。定义了集热比、有效蓄热体积平均温度、水箱热量取充比和热损比等参数对系统进行了分析与评价。研究表明:与传统的太阳能供暖固定容积单水箱温度分层蓄热系统相比,在整个供暖季,二级水箱变容积蓄热系统的热损失减少了17.2%,取充比增加了6.3%,?效率提高了6.6%,辅热能耗减少了9.5%;在供暖初期,二级水箱变容积蓄热系统的水箱温度响应时间缩短了54.9%,可更灵活快速地用于供热。二级水箱变容积蓄热系统有利于调节供暖季不同时期的供需匹配,具有良好的节能效果,可进一步为太阳能供暖系统的设计与应用提供指导。     

严寒C区太阳能热水采暖系统设计参数匹配的研究

以太阳能热水采暖系统蓄热水箱的容积与太阳能集热器的集热面积的匹配关系为研究对象,通过数值模拟的方法,以严寒C区的赤峰地区为例,参考赤峰地区的逐时气象数据,以太阳能热水采暖系统的集热效率、太阳能贡献率为优化目标,对蓄热水箱的容积与太阳能集热器的集热面积的比值(RVA)、蓄热水箱保温层厚度等设计参数进行了优化研究.研究结果...     

Investigation of thermal performance of a ground coupled heat pump system with a cylindrical energy storage tank

An analytical and computational model for a solar assisted heat pump heating system with an underground seasonal cylindrical storage tank is developed. The heating system consists of flat plate solar collectors, an underground cylindrical storage tank, a heat pump and a house to be heated during winter season. Analytical solution of transient field problem outside the storage tank is obtained by the application of complex finite Fourier transform and finite integral transform techniques. Three expressions for the heat pump, space heat requirement during the winter season and available solar energy are coupled with the solution of the transient temperature field problem. The analytical solution presented can be utilized to determine the annual variation of water temperature in the cylindrical store, transient earth temperature field surrounding the store and annual periodic performance of the heating system. A computer simulation program is developed to evaluate the annual periodic water and earth temperatures and system performance parameters based on the analytical solution. Copyright © 2003 John Wiley & Sons, Ltd.     

以空气为携热介质的开式太阳能蓄能热泵循环研究与分析

以空气为携热介质的开式太阳能吸收式热泵系统为研究对象，在原有制冷循环基础上，根据冬季蓄能热泵循环运行特点对系统进行改进；并以西安地区为例对循环进行计算和分析，探讨其蓄能情况和影响系统工作性能的因素。     

Thermal performance of a solar-assisted heat pump drying system with thermal energy storage tank and heat recovery unit

Thermal performance parameters for a solar-assisted heat pump (SAHP) drying system with underground thermal energy storage (TES) tank and heat recovery unit (HRU) are investigated in this study. The SAHP drying system is made up of a drying unit, a heat pump, flat plate solar collectors, an underground TES tank, and HRU. An analytical model is developed to obtain the performance parameters of the drying system by using the solution of heat transfer problem around the TES tank and energy expressions for other components of the drying system. These parameters are coefficient of performances for the heat pump (COP) and system (COPs), specific moisture evaporation rate (SMER), temperature of water in the TES tank, and energy fractions for energy charging and extraction from the system. A MATLAB program has been prepared using the expressions for the drying system. The obtained results for COP, COPs, and SMER are 5.55, 5.28, and 9.25, respectively, by using wheat mass flow rate of 100 kg h⁻¹, Carnot efficiency of 40%, collector area of 100 m², and TES tank volume of 300 m³ when the system attains periodic operation duration in fifth year onwards for 10 years of operation. Annual energy saving is 21.4% in comparison with the same system without using HRU for the same input data.     

冰源热泵系统在设施水产养殖中的技术经济性研究

针对目前刺参养殖的水温调控系统能耗大及适用性差等问题,提出基于冰源热泵的高效清洁供热及结合跨季节蓄冷实现全年冷热管理的技术思路,采用冰源热泵系统和跨季节蓄冷型冰源热泵系统对养殖水体温度进行调控,建立模型定量对比分析系统的运行能效及技术经济性.结果表明:(1)冰源热泵系统供热和供冷时的性能系数分别为3.33和3.39,全...     

Experimental investigation of thermal performance of a solar assisted heat pump system with an energy storage

An experimental solar assisted heat pump space heating system with a daily energy storage tank is designed and constructed, and its thermal performance is investigated. The heating system basically consists of flat plate solar collectors, a heat pump, a cylindrical storage tank, measuring units, and a heating room located in Gaziantep, Turkey (37.1°N). All measurements are automatically collected as a function of time by means of a measurement chain feeding to a data logger in combination with a PC. Hourly and daily variations of solar radiation, collector performance, coefficient of performance of the heat pump (COP_HP), and that of the overall system (COP_S) are calculated to evaluate the system performance. The effects of climatic conditions and certain operating parameters on the system performance parameters are investigated. COP_HP is about 2.5 for a lower storage temperature at the end of a cloudy day and it is about 3.5 for a higher storage temperature at the end of a sunny day, and it fluctuates between these values in other times. Also, COP_S turns out to be about 15–20% lower than COP_HP. Copyright © 2004 John Wiley & Sons, Ltd.     

Optimal sizing of a heat pump/thermal storage system based on the linear programming method

An optimal planning method is proposed for a heat pump/thermal storage system that utilizes time-of-use pricing of the electrical utility. Equipment capacities are determined so as to minimize the annual total cost in consideration of system's operational strategies for energy demand requirements. This optimal planning problem is solved by the linear programming method. Through a numerical study on a heat pump/thermal storage system for a commercial building, the effect of thermal storage tank is investigated on the long-term economics of the system. A parametric study is also performed with respect to the initial capital unit cost of thermal storage tank. The relation is clarified among the optimal capacities of thermal storage tank and other pieces of equipment. It is ascertained that this optimal planning method is a useful tool for evaluating the economic properties of heat pump/thermal storage systems.     

Experimental results of a sensible heat storage system for residential and light commercial application

This paper presents the performance results for a sensible heat storage system. The system under study operates as an air source heat pump which stores the compressor heat of rejection as domestic hot water or hot water in a storage tank that can be used as a heat source for providing building heating. Although measurements were made to quantify space cooling, space heating, and domestic water heating, this paper emphasizes the space heating performance of the unit. The heat storage system was tested for different indoor and outdoor conditions to determine parameters such as heating charge rate, compressor power, and coefficient of performance (COP). The thermal storage tank was able to store a full charge of heat. The rate of increase of storage tank temperature increased with outdoor temperature. The heating rate during a charge test, best shown by the normalized rate plots, increased with evaporating temperature due to the increasing mass flow rate and refrigerant density. At higher indoor temperature during the discharge tests, the rate of decrease of storage tank temperature was slower. Also, the discharge heating rate decreased with time since the thermal storage tank temperature decreased as less thermal energy became available for use. Copyright © 1999 John Wiley & Sons, Ltd.     

相变材料在太阳能-地源热泵系统中的应用

针对太阳能-地源热泵的供热量波动性问题,在系统中设置蓄热装置,利用相变蓄热材料具有蓄、放热的特性,达到调节系统供热量和稳定性的目的。通过对带有蓄热装置的太阳能-地源热泵系统的运行模式及其转换条件的研究,使系统运行处于最佳运行工况,提高了系统的总平均供热COP值,并使之达到6.5。