空气源热泵成为可靠供暖热源技术的探讨

分析了空气源热泵在山西省北部供暖现状及存在的问题,介绍了空气源热泵供暖系统的几种改进措施,提出通过对空气源热泵直接供暖系统上增设一定容量的蓄热水箱,而在执行峰谷电价的地区则增设电锅炉和蓄热水箱,使空气源热泵成为严寒地区可靠的供暖热源。     

严寒地区区域供暖系统优化方案技术经济性分析

严寒地区既有供暖系统改造作为我国老旧小区综合改造和性能提升的重要内容,是缓解我国环境问题和资源紧张的重要途径和关键环节。基于“煤改气”、“煤改电”政策对燃气锅炉供暖系统、空气源热泵复合供暖系统进行技术与经济分析,旨在为我国严寒地区区域供暖提供重要的参考价值。     

空气源热泵耦合太阳能集热器运行能效评价

寒冷地区冬季气温低,供暖系统尤为重要,近几年伴随着能源技术的成熟,空气源热泵开始得到广泛应用。在单一供暖系统的基础上,也出现了多能联合分户供暖系统,其中比较常见的有空气源热泵与太阳能集热器联合。论文以相应的耦合系统为对象,就寒冷地区供暖季空气源热泵单独供暖以及与太阳能集热器系统耦合供暖的情况进行了分析,结果表明,太阳能集热器的应用,可以将运行能效提高8.9%。     

基于TRNSYS的太阳能-空气能高效供暖系统仿真模拟研究

针对内蒙地区农牧民居住建筑设计了一套户用太阳能-空气能高效供暖系统，使用TRNSYS软件搭建了供暖系统模型，模拟供暖季供热系统运行情况，从系统能耗、太阳能集热效率、供热性能系数等方面对比分析了该系统与太阳能复合空气源热泵供暖系统的性能。结果表明，与太阳能复合空气源热泵供暖系统相比，该系统的太阳能集热效率、太阳能转化总效率、供暖季制热性能系数分别提高了34.65%、51.15%、22.62%,该系统利用蓄热水箱低品位热源实现了太阳能高效供热，且节能效果显著。     

寒冷地区空气源热泵耦合太阳能集热器系统供暖季运行能效评价

近年来寒冷地区空气源热泵热水器使用逐渐增多,多能联合分户供暖系统陆续出现。目前热泵热水器产品的能效采用瞬时COP表示,寒冷地区供暖季环境温度波动较大,空气源热泵系统在变工况下运行时难以用瞬时COP来表示其实际的运行能效。试验以空气源热泵与太阳能集热器耦合系统为测试平台,分别测试分析空气源热泵热水器单独供暖和空气源热泵耦合太阳能集热器系统在寒冷地区供暖工况下的制热情况。结合整个供暖季气象数据和建筑供暖负荷,计算得出供暖工况下单空气源热泵热水器运行季节能效系数SPFh为2.48,空气源热泵耦合太阳能集热器运行季节能效系数SPFs为2.70,太阳能集热器使系统供暖季节运行能效提高了8.9%。     

CO2-R134a复叠式空气源热泵系统工程设计与应用

CO₂-R134a复叠式空气源热泵在严寒地区冬季可以实现稳定制热,该系统能耗较常规空气源热泵系统制热能效更高,可以作为偏远地区厂站供热热源,且可以节约运营费用。本文通过实际项目案例进行技术和经济分析,探讨CO₂-R134a复叠式空气源热泵系统在城郊或偏远无集中热力管网区域的应用,为严寒地区在低碳、减排政策下,实现低温环境制热选择提供新思路。     

空气源热泵供暖工程设计要点分析

空气源热泵供暖系统的设计对其实际运行效果和节能性有较大影响。本文根据我国不同地区气候特性,从空气源热泵供暖工程全生命周期成本出发,研究了适用的最经济平衡点温度计算方法,用于确定空气源热泵机组和辅助热源承担热负荷的比例。相关最经济平衡点计算方法已在工程建设协会标准《空气源热泵供暖工程技术规程》得到应用,为我国不同地区空气源热泵供暖工程设计提供指导和依据,保证系统运行效果的同时提高系统的经济性和节能性,推动其在我国不同地区的应用。     

严寒C区既有公共建筑围护结构节能改造及供暖系统优化实例分析

根据严寒C区公共建筑能耗情况,综合考虑了建筑朝向、窗墙比、墙体外保温材料、窗户的类型等因素,以乌鲁木齐市某2653平方米的办公楼为例,对办公楼的围护结构进行了节能改造设计。本文对比了燃气辅助太阳能供暖、燃气辅助太阳能空气能复合供暖、空气源热泵供暖三种供暖系统,对办公楼的供暖系统进行了优化设计,探讨了办公楼的节能改造效果和供暖系统的经济性。结果表明,办公楼围护结构经过节能改造后节能率可达到74%,采用燃气辅助太阳能空气能复合供暖系统一个采暖周期可节约运行费用4.19万元,同时可节约41.58吨标准煤,具有显著的经济和环境效益。     

冷凝蓄热器蓄放热过程模拟研究

为解决传统单级压缩空气源热泵在严寒地区制热性能差、极低环境温度下无法运行的问题,提出了一种基于相变蓄热的空气源热泵联合低温热水地板辐射供暖系统.通过构建系统模型,对关键部件冷凝蓄热器的蓄放热过程进行了研究,分析了冷凝蓄热器的动态运行特性.研究结果表明:冷凝蓄热器连续蓄热14 h后,平均蓄热功率为7.19 kW,COP为...     

地板供暖用空气源热泵产品标准关键问题研究

以空气源热泵为热源设备、辐射地板为末端的供暖系统广泛应用于我国大部分气候区的农村与城镇住宅、办公等建筑中,而用于该类供暖系统的空气源热泵机组尚无统一的产品标准。针对不同气候区的供暖需求,通过分析,给出了典型地区典型建筑的负荷模型、不同负荷率下空气源热泵使用侧的供水温度和制热运行时的室外工况条件;根据空气源热泵实测数据,建立了性能模型,分析所提出的该类空气源热泵机组的名义工况、季节性能评价工况,以及名义工况性能系数COPh与综合部分负荷性能系数IPLV(H)限定值,可为产品标准制定提供参考。     

Exergetic performance assessment of a solar photovoltaic thermal (PV/T) air collector

In this paper, an attempt is made to evaluate the exergetic performance of a solar photovoltaic thermal (PV/T) air collector. A detailed energy and exergy analysis is carried out to calculate the thermal and electrical parameters, exergy components and exergy efficiency of a typical PV/T air collector. Some corrections are done on related heat loss coefficients. An improved electrical model is used to estimate the electrical parameters of a PV/T air collector. Further, a modified equation for the exergy efficiency of a PV/T air collector is derived in terms of design and climatic parameters. A computer simulation program is also developed to calculate the thermal and electrical parameters of a PV/T air collector. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally, parametric studies have been carried out. It is observed that the modified exergy efficiency obtained in this paper is in good agreement with the one given by the previous literature. It is also found that the thermal efficiency, electrical efficiency, overall energy efficiency and exergy efficiency of PV/T air collector is about 17.18%, 10.01%, 45% and 10.75% respectively for a sample climatic, operating and design parameters.     

浅谈建筑太阳能光电热综合利用

本文主要介绍了建筑太阳能光电热综合利用一体化系统类型以及国内外发展现状,对今后建筑太阳能光电热综合利用一体化系统的发展方向提出了建议。     

水冷型PV/T系统的高效利用与发展现状

在光伏光热系统(PV/T)中为提高其电效率并高效利用低品位热能,近年来对于冷却工质及其工作方式的研究越来越多。其中,水冷式以其方便直接使用、无需二次换热、良好的光学特性和高热容量等优点,受到了广泛的理论研究和实验测试。通过以效率的视角探究光伏覆盖率、背管分布形式等影响流体冷却能力的因素,并结合相变PV/T、PV/T矩阵等PV/T未来发展新趋势,为今后水冷型PV/T系统进一步高效实验提供了研究方向。     

Condenser heat recovery with a PV/T air heating collector to regenerate desiccant for reducing energy use of an air conditioning room

This paper presents an experimental test along with procedures to investigate the validity of a developed simulation model in predicting the dynamic performance of a condenser heat recovery with a photovoltaic/thermal (PV/T) air heating collector to regenerate desiccant for reducing energy use of an air conditioning room under the prevailing meteorological conditions in tropical climates. The system consists of five main parts; namely, living space, desiccant dehumidification and regeneration unit, air conditioning system, PV/T collector, and air mixing unit. The comparisons between the experimental results and the simulated results using the same meteorological data of the experiment show that the prediction results simulated by the model agree satisfactorily with those observed from the experiments. The thermal energy generated by the system can produce warm dry air as high as 53 °C and 23% relative humidity. Additionally, electricity of about 6% of the daily total solar radiation can be obtained from the PV/T collector in the system. Moreover, the use of a hybrid PV/T air heater, incorporated with the heat recovered from the condenser to regenerate the desiccant for dehumidification, can save the energy use of the air conditioning system by approximately 18%.     

A heat pipe photovoltaic/thermal (PV/T) hybrid system and its performance evaluation

Building-integrated photovoltaic/thermal (BIPV/T) system has been considered as an attractive technology for building integration. The main part of a BIPV/T system is PV/T collector. In order to solve the non-uniform cooling of solar PV cells and control the operating temperature of solar PV cells conveniently, a heat pipe photovoltaic/thermal (PV/T) hybrid system (collector) has been proposed and described by selecting a wick heat pipe to absorb isothermally the excessive heat from solar PV cells. A theoretical model in terms of heat transfer process analysis in PV module panel and introducing the effectiveness-number of transfer unit (?-NTU) method in heat exchanger design was developed to predict the overall thermal-electrical conversion performances of the heat pipe PV/T system. A detailed parametric investigation by varying relevant parameters, i.e., inlet water temperature, water mass flow rate, packing factor of solar cell and heat loss coefficient has been carried out on the basis of the first and second laws of thermodynamics. Results show that the overall thermal, electrical and exergy efficiencies of the heat pipe PV/T hybrid system corresponding to 63.65%, 8.45% and 10.26%, respectively can be achieved under the operating conditions presented in this paper. The varying range of operating temperature for solar cell on the absorber plate is less than 2.5 °C. The heat pipe PV/T hybrid system is viable and exhibits the potential and competitiveness over the other conventional BIPV/T systems.     

Comments on “Analytical expression for electrical efficiency of PV/T hybrid air collector” by S. Dubey,G.S. Sandhu,and G.N. Tiwari

In this short communication, a theoretical attempt has been made and the analytical expression developed by Dubey, Sandhu, and Tiwari [2009. “Analytical Expression for Electrical Efficiency of PV/T Hybrid air Collector.” Applied Energy 86: 697–705.] for temperature-dependent electrical efficiency of air type PV/T collector has been corrected. The analyses have indicated that their efficiency expression only considers the effects of solar intensity. However, it is unequivocal from the governing equations that the ambient temperature is another variable that should be in the efficiency expression as an initial condition of the energy balance equation of flowing air. Although they asserted that the electrical efficiency of the system has been evaluated with respect to the variations in solar intensity and ambient temperature for a typical day in the month of April 2008 for New Delhi condition, the results clearly show that the ambient temperature has not been taken into account in their study. Their expression not including a term for ambient temperature proves our statement. In the present work, the corrected version of the efficiency expression is given.     

石墨填充式PV/T系统光电光热性能试验

设计制作了一种以高导热材料——石墨为填充介质的新型PV/T结构,并搭建了该PV/T系统的光电光热性能综合试验台,在大连地区对其光电光热性能进行了试验研究。研究结果表明：在天气晴朗的情况下,与普通PV板相比,石墨填充式PV/T系统的输出功率相对提高可达120.67%;系统的瞬时热效率可达28.68%;系统水经过一天的循环,可使水箱温度上升至38℃。     

PV/T系统电热性能的实验研究

介绍了PV/T系统组成的原理,针对PV/T系统的电热性能进行了实验研究,并对实验数据进行了处理。计算出了不同参数下该PV/T系统的热效率和电效率,分析了这些参数对系统热效率的影响,以及PV/T模块表面温度对系统电效率的影响。     

新型太阳能光伏—热泵复合建筑供能系统及其性能实验研究

将基于平板微热管阵列技术的新型水冷光伏光热(Photoveltaic-thermal,PV/T)系统与双热源热泵相结合,提出1种新型太阳能光伏—热泵复合建筑供能系统。本文介绍了该复合建筑供能系统的组成、工作原理、运行模式及实验台的设计,并对PV/T系统与双热源热泵联合运行模式进行了实验研究与性能分析。PV/T系统峰值功率为1 170 W,压缩机功率为1HP的系统,在室外环境平均气温为4.0℃,平均辐照度684 W/m2条件下,热泵平均制热COP为2.7,平均发电功率为620.5W,平均发电效率为11.7%,全天(9:00~15:00)发电量为4.39 k Wh,平均集热效率为22.3%,光伏光热综合效率为34.1%。实验结果表明该系统能充分利用太阳能和热泵各自优势,通过能源互补,提高系统综合利用效率,满足建筑所需的多种用能需求,在推广可再生能源利用和建筑节能方面具有重要意义。     

An environmental and thermodynamic analysis to select R22 alternative working fluids

R22, a hydrochlorofluorocarbon (HCFC), is used widely in the air-conditioning and refrigeration industry; however, it is being phased out along with other HCFCs, due to concerns about its impact on ozone depletion. In the EEC countries its production, commercialization and use will be forbidden before the end of 1999.

According to the AREP (R22 Alternative Refrigerants Evaluation Program) project, coordinated by the Air-conditioning and Refrigeration Institute (ARI) a group of substances has been pointed out as potential ozone-free R22 alternatives.

In this paper some working fluids, among those one considered by AREP, will be evaluated by means of a comparative thermodynamic analysis. Furthermore, particular interest will be paid to the environmental global impact joined to the substitution. To this aim, the Total Equivalent Warming Impact (TEWI) will be used as a tool to evaluate both direct and indirect contributions to the “greenhouse effect” linked to an operating vapour compression plant.