基于TRNSYS的空气源热泵辅助太阳能热水系统优化研究

为实现空气源热泵辅助太阳能热水系统中关键参数的优化匹配,基于TRNSYS动态模拟平台建立完整的空气源热泵辅助太阳能热水系统模型。以系统生命周期成本为目标函数,以集热器面积、集热器倾角、水箱容积及热泵功率为优化变量,借助GENOPT软件调用Hooke-Jeeves算法对系统各变量进行同步优化,并对各优化变量进行敏感性分析。以西昌市某学生宿舍的空气源热泵辅助太阳能热水系统为研究对象进行优化。研究结果表明,优化后的COPsys普遍提高,系统性能得到明显改善,系统全年运行费用缩减,全年节电率高达9.11%。并在此基础上提出关键参数的推荐匹配原则:单位集热面积水箱容积为70 L/m~2,单位集热面积热泵功率为60 W/m~2,最佳集热器倾角为φ-6°(φ为当地纬度)。对空气源热泵辅助太阳能热水系统进行设计时,可依据以上匹配原则对热泵功率、集热器面积、水箱容积、集热器倾角按照先后顺序进行优化。研究结果可为空气源热泵辅助太阳能热水系统的优化设计提供理论依据。     

太阳能-地源热泵复合系统的性能分析及优化

以应用于西安市周边地区农村住宅的太阳能-地源热泵复合系统为研究对象，利用TRNSYS软件对该复合系统进行建模。首先，对复合系统中主要部件的参数计算方式进行了详细阐述；其次，对复合系统中的太阳能集热器倾角与蓄热水箱容积进行了分析；最后，从太阳能集热系统集热量、地源热泵系统能耗及能效比(COP)等角度对复合系统的运行工况进行优化。研究结果表明：在整个供暖期，在集热器倾角为52°、蓄热水箱容积为0.45 m³时，整个复合系统的总能耗最低；优化后的复合系统的总能耗为1089.6 kWh，地源热泵系统在运行期间的平均COP为3.5371，太阳能集热器的累计集热量为327.3 kWh。研究结果为西安市及其周边地区应用太阳能-地源热泵复合系统的设计及优化奠定了基础，对实现碳达峰及碳中和目标具有重要意义。     

双水箱太阳能集中热水系统关键参数优化及建筑类型的适用性研究

为对供热水箱容积、供热水箱控制最低水位、补水泵流量、集热水箱放水温度等关键参数进行系统优化,建立典型的双水箱太阳能集中热水系统仿真模型,以太阳能保证率和集热效率为主优化指标。结果表明:部分工况下供热水箱容积的增大会引起太阳能保证率的增大,但集热器的集热效率会有所减小;对于供热水箱通过水位控制的双水箱太阳能集中热水系统,建筑类型对系统补水泵流量的影响较大;对于集热水箱到供热水箱的热水通过温差控制的热水系统,放水温度应大于用户用水温度;双水箱太阳能集中热水系统,更适于24 h连续供水的建筑类型。     

基于交互正交试验的热水系统太阳能保证率影响因素研究

为研究太阳能热水系统(SHWS)关键参数及其交互作用对系统性能的影响程度,建立完整的太阳能热水系统模型,采用正交试验法,以太阳能保证率为目标参数,选取集热倾角、集热面积、水箱容积和循环流量为影响因素,通过极差分析和方差分析研究各因素及其交互作用对太阳能保证率的影响程度。研究结果表明,在实际太阳能热水系统设计与优化时,应着重考虑所选4个关键参数和水箱容积与循环流量的交互作用,可以不考虑集热面积与水箱容积的交互作用。可为太阳能热水系统的优化设计提供依据。     

蓄热水箱水温和水箱体积对太阳能集热系统的性能影响分析

采用实验和模拟计算方法对太阳能集热系统蓄热水箱的水温和水箱体积影响因素开展探究，分析日有用得热量、集热器功率和水箱内平均温度等参数随水箱初始温度和水箱体积的变化规律。研究结果表明：水箱初始温度从10.34℃增加到29.88℃时，日有用得热量减少了19.52%；换算成日太阳辐照量为17MJ/m2时的储热水箱中水的温升值下降了17.66%，储热水箱结束水温下降了10.73%；单位面积日有用得热量减少了17.64%。通过TRNSYS模拟软件，分析出太阳能集热系统全年运行工况时的水箱变量参数对系统性能的影响，获得了日有用得热量、集热器功率和水箱内平均温度的变化规律。通过选取不同月份的若干个时段进行对比分析，得出水箱体积对太阳能供热系统的影响较水箱初始温度大；当下调水箱初始温度和缩小水箱体积时，日有用得热量提升，但集热器功率降低；当上调水箱初始温度和缩小水箱体积时，水箱内平均温度升高；且随着太阳能集热系统运行时间的累加，水箱初始温度和水箱体积对上述各性能参数的影响减弱。日有用得热量、集热器功率和水箱内平均水温随着季节变化明显，秋季和冬季气候下的日有效得热量，集热器功率和水箱内平均水温均低于春季和夏季。     

阳台式太阳能热水系统性能及分析

对阳台式太阳能热水系统进行了应用效果的测试:当太阳辐射量为17 MJ/m2时,太阳能集热系统单位轮廓采光面积的日有用得热量为4.73 MJ/m2,小于评定合格值;热水系统温升为20℃,小于评定合格值;贮水箱保温性能△t sd为6.2℃,符合评定合格值,水箱保温良好;贮水箱最终出水温度达到51℃,能满足配水点最低水温要求。分析表明,造成阳台式太阳能热水系统集热效果达不到合格标准是由于集热器安装倾角过大、上下层集热器的自遮挡和建筑的隔墙遮挡所致。文章提出,应用在高层建筑的集热器可分散设置在屋顶和南向外墙的外挑板上,并采取上下错层的布置方式。     

基于TRNSYS的太阳能光热系统数值模拟和优化

文中利用TRNSYS模拟软件建立太阳能光热系统模型,并在理论计算和实测数据验证该模型的基础上,模拟了气象条件、集热器安装角度、集热器面积和水箱容积等因素的变化对水箱平均温度和集热系统效率的影响;设计正交实验,给出了集热器面积与水箱容积的最佳组合,在理论分析与实验模拟的基础上,提出了太阳能光热系统的优化。     

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.     

高寒地区户用太阳能沼气发酵系统的设计

以呼和浩特地区冬季环境条件和太阳能辐射数据为依据,设计了一套适用于严寒地区冬季气温条件下的户用太阳能沼气发酵系统。沼气发酵池体积为6 m3,通过计算沼气池的热负荷,得出维持池内正常产气所需的热量为37.7 MJ;采用真空管太阳能集热器循环系统,太阳能集热器的集热面积为5.17 m2,所需真空管数量为50根,储热水箱的容积为0.72 m3。     

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。研究结果表明,在RVA为50～150 L/m~2的条件下,赤峰地区的太阳能热水采暖系统可获得较为理想的集热效率。研究结果可为严寒C区太阳能热水采暖系统的设计提供参考。     

Study on performance of solar assisted air source heat pump systems for hot water production in Hong Kong

This paper reports the investigation results on application of the solar assisted air source heat pump systems for hot water production in Hong Kong. A mathematical model of the system is developed to predict its operating performance under specified weather conditions. The optimum flow rate from the load water tank to the condenser is proposed considering both the appropriate outlet water temperature and system performance. The effect of various parameters, including circulation flow rate, solar collector area, tilt angle of solar collector array and initial water temperature in the preheating solar tank is investigated, and the results show that the system performance is governed strongly by the change of circulation flow rate, solar collector area and initial water temperature in the preheating solar tank.     

OPTIMIZATION OF DOMESTIC SOLAR WATER HEATING SYSTEM

TRNSYS program was used to simulate the performance of a thermosyphon type domestic solar water heating system which is used in the West Bank. The system installation and operation parameters were optimized including collector tilt angle, the hot water storage tank volume and location relative to the collector, and the hot water consumption pattern and daily rate.     

Experimental investigation and performance analysis on a solar adsorption cooling system with/without heat storage

A solar adsorption cooling system which can be switched between a system with heat storage and a system without heat storage was designed. In the system with heat storage, a heat storage water tank was employed as the link between the solar collector circulation and the hot water circulation for the adsorption chillers. However, the heat storage water tank was isolated in the system without heat storage, and the hot water was directly circulated between the solar collector arrays and the adsorption chillers. It was found that the inlet and outlet temperatures for the solar collector arrays and the adsorption chillers in the system without heat storage were more fluctuant than those of the system with heat storage. Also found was that the system with heat storage operated stably because of the regulating effect by the heat storage water tank. However, under otherwise similar conditions, the cooling effect of the system without heat storage was similar to that of the system with heat storage. Compared with the system with heat storage, the system without heat storage has the advantages of higher solar collecting efficiency as well as higher electrical COP.     

Modeling of the CSU heating/cooling system

This paper resents a thermal simulation of the Colorado State University solar house. A computer model of the solar energy system was developed and computer runs were made using one year of meteorological data to determine the important design features. The system consists of a flat plate solar collector, main storage tank, service hot water storage tank, auxiliary heater, absorption air conditioner with cooling tower and heat exchangers between the collector and storage, storage and service hot water tank and storage and residence. This system very closely models the CSU house in operating mode one.The results are in the form of monthly integrated values for the pertinent energy quantities. In addition, results are presented which show the effect on the system performance of the collector tilt, collector area and number of covers.     

Identifying key design parameters of the integrated energy system for a residential Zero Emission Building in Norway

This study examined an integrated solution of the building energy supply system consisting of flat plate solar thermal collectors in combination with a ground-source heat pump and an exhaust air heat pump for the heating and cooling, and production of domestic hot water. The supply energy system was proposed to a 202 m² single-family demo dwelling (SFD), which is defined by the Norwegian Zero Emission Building standard. The main design parameters were analyzed in order to find the most essential parameters, which could significantly influenced the total energy use. This study found that 85% of the total heating demand of the SFD was covered by renewable energy. The results showed that the solar energy generated by the system could cover 85–92% and 12–70% of the domestic hot water demand in summer and winter respectively. In addition, the solar energy may cover 2.5–100% of the space heating demand. The results showed that the supply air volume, supply air and zone set point temperatures, auxiliary electrical volume, volume of the DHW tank, orientation and tilt angle and the collector area could influenced mostly the total energy use.     

真空管热水器倾角的数值模拟分析

利用fluent软件中的太阳载荷模型对真空管家用太阳热水器进行了三维数值模拟计算,分析了30°、45°、60°倾角下真空管热水器内的流场和温度场随加热时间的变化及传热和流动过程。结果表明,真空管热水器在加热期间,在真空管管口的上壁面出现温度最大值,水箱内真空管管口以下水的温度相对于管口以上的温度分层很明显,水箱内真空管管口以上的热水温度几乎相同,说明水箱内管口以上的水进行了充分混合;对于30°和45°倾角的系统,随着加热时间的增加,水箱内管口以下的水温与管口以上的水温从10 K增加到30 K,以45°倾角为例,当考虑了水箱内管口以下的冷水区时,随着加热时间的增加,真空管与水箱内的温差从0.73 K增大到1.13 K,仅考虑水箱内均匀分布的三点时,随着加热时间的增加,真空管与水箱内的温差从0.15 K减小到了0.03 K;随着系统倾角从30°增加到60°,水箱内管口以下的冷水区域在逐渐减小。因此,为了减小水箱底部的冷水区,插入水箱内的真空管应尽可能短。     

Performance investigation on a thermal energy storage integrated solar collector system using nanofluid

The effect of Fe nanofluid on the performance enhancement on solar water heater integrated with thermal energy storage system is investigated experimentally. A 0.5% wt fraction of Fe nanoparticle was synthesized with the mixture of water/propylene‐glycol base fluid. The experimental implementation utilized 40‐nm‐size Fe nanoparticle, 15 ° collector tilt angle, and 1.5 kg/min mass flow rate heat‐transfer fluid circulation. The system efficiency reached 59.5% and 50.5% for with and without nanofluid. The water tank temperature was increased by 13 °C during night mode. The average water tank temperature at night mode was 47.5 °C, while the average ambient temperature was 26 °C. The Fe nanofluid improved the system working duration during night mode by an average of 5 h. The techno‐economic analysis results showed a yearly estimated cost savings of 28.5% using the Fe nanofluids as heat transfer fluid. The embodied energy emission rate, collector size, and weight can be reduced by 9.5% using nanofluids. Copyright © 2016 John Wiley & Sons, Ltd.     

非跟踪低倍聚光热管式真空管集热器的实验研究

太阳能是一种取之不尽用之不竭的清洁能源,但存在分散性强、能量密度低、不稳定等特点,因此为了得到高能量密度和稳定的能量供应,需要解决聚光和储能两大问题。针对这两个问题,本文采用非跟踪低倍聚光的集热器和保温效果良好的储热油箱,提出了一种非跟踪低倍聚光热管式真空管集热器;基于几何光学原理,模拟了热管式真空管和半圆聚光器的不同放置方式和位置的聚光效率,制作了半圆形聚光热管式真空管集热器系统,选择了合适的储热油箱并进行了保温效果的理论计算;最后对该系统进行了集热性能测试实验。实验结果表明,在半圆形聚光器的聚光下,系统的瞬时效率截距为0.66,热损系数为2.53 W/(m2•℃)。该系统完全能够满足人们的日常生活用热的需求,具有良好的应用前景。     

Experimental investigation and theoretical analysis of the solar adsorption cooling system in a green building

A solar adsorption cooling system was constructed in the green building of Shanghai Institute of Building Science. The system consisted of evacuated tube solar collector arrays of area 150 m², two adsorption chillers with nominal cooling capacity of 8.5 kW for each and a hot water storage tank of 2.5 m³ in volume. A mathematical model of the system was established. According to experimental results under typical weather condition of Shanghai, the average cooling capacity of the system was 15.3 kW during continuous operation for 8 h. The theoretical analysis of the system was verified and found to agree well with the experimental results. The performance analysis showed that solar radiant intensity had a more distinct influence on the performance of solar adsorption cooling system as compared with ambient temperature. It was observed that the cooling capacity increased with the increase of solar collector area, whereas, solar collecting efficiency varied quite contrary. With the increase of water tank volume, cooling capacity decreased, while, the solar collecting efficiency increased. The system performances can be enhanced by increasing the height-to-diameter ratio of water tank. Additionally, it was observed that solar collecting efficiency decreased with the increase of the initial temperature of water in the tank; however, cooling capacity varied on the contrary. Also can be seen is that optimum nondimensional mass flow rate is 0.7 when the specific mass flow rate exceeds 0.012 kg/m² s.