太阳能集热室内供暖现状及展望

太阳能替代化石能源供暖能够减少对传统能源的消耗,降低污染气体排放,具有研究和应用价值。从太阳能资源特点、传统供暖与太阳能集热室内供暖现状、太阳能集热室内供暖系统优势以及集热器特点等方面进行分析,并针对宜昌地区的应用进行探讨。     

相变储能太阳能热泵系统的试验研究

文章建立了相变储能太阳能热泵系统试验平台,介绍了系统的运行方式以及各个部分的运行原理,选取典型日进行试验,并对试验数据进行分析。分析结果表明:相变储能太阳能热泵系统能够满足北方农村的供暖需求,可以保证白天室内的温度达到22℃,COP的最大值为6.3;太阳能热泵系统停止工作后,相变储能箱可以保证室内温度达到供暖的需求温度7 h,起到了"削峰填谷"的作用,运行费用显著降低;相变储能太阳能热泵系统解决了单纯电加热供暖方式费用高、能耗高的问题,具有显著的节能性。     

西北新农村建筑太阳能主动供暖试验研究

为了降低西北新农村建筑采暖的能耗,改善室内生活环境,通过试验研究了太阳能主动供暖和传统小型燃煤锅炉供暖的西北新农村建筑的室内热环境、空气质量和采暖能耗的差异。研究结果表明:在室外环境最低温度为-16.2℃条件下,太阳能主动供暖建筑室内平均温度和平均辐射温度分别高出对比建筑5.4℃和3.3℃;在天气晴朗情况下,当室外环境的平均温度高于4.2℃且室外环境的最低温度高于-1.6℃时,仅利用太阳能进行供暖即可满足西北新农村建筑的供暖需求;太阳能主动供暖建筑室内CO,NO2,SO2,CO2及可吸入颗粒物PM10的浓度分别是对比建筑的0.45倍、0.48倍、0.56倍、0.59倍和0.5倍;经过分析得到太阳能主动供暖时室内环境温度与散热片内热水温度以及室外环境温度的二元线性关系;太阳能主动供暖的节能率为86.6%。     

太阳能集热墙与地下室复合系统冬季供暖试验研究

提出一种适用于被动式太阳能空气供暖的地下室蓄热系统,并对西北严寒地区采用该系统的农村住宅进行供暖试验研究。通过试验,分析太阳能集热墙与地下室复合系统对室内热环境的影响。试验结果表明:有太阳能集热墙与地下室复合系统的房间内平均空气温度比对比房的室内空气平均温度高7.5℃,最高温差达13.6℃,最低温差为2.5℃。通过对太阳房供暖节能率的分析计算得出其节能率为62.3%,验证在该地区建立太阳能集热墙与地下室复合系统建筑的可行性和经济性。     

太阳能-空气源双能源复合供暖在严寒地区农村住宅中的应用研究

针对空气源热泵热风机在室外低温环境下供暖性能衰减，导致室内冬季供暖效果变差等问题，为充分发挥资源优势，提出了一种太阳能-空气源双能源复合高效集成装置，实现了太阳能集热器与低温空气源热泵热风机联合供暖。介绍了该集成装置的技术原理和控制策略，通过TRNSYS软件对该集成装置在哈尔滨地区农村住宅的供暖效果进行了研究，并对该集成装置供暖和低温空气源热泵热风机单独供暖的效果进行了对比分析。研究结果表明：太阳能-空气源双能源复合高效集成装置实现了太阳能与空气源两种能源更为合理的供暖时段匹配。在整个供暖季，与低温空气源热泵热风机单独供暖相比，该集成装置的供暖效果更好且能耗更低，其系统总能耗降低了2034.8 kWh，制热能效比提升了35.06%。     

严寒地区太阳能-空气源热泵系统供暖实验研究

针对严寒地区所构建的太阳能-空气源热泵系统供暖实验装置,进行热泵独立运行及蓄热水箱-热泵双热源联合运行的供暖特性研究。结果表明:使用空气源热泵单独供暖时,当室外温度低于-12℃时系统COPs达到最低,无法满足室内采暖需求;当室外温度在-12～-7℃之间时,室内采暖需求虽可得到满足,但系统COPs仅为1.10～1.44,节能效果不明显;当室外温度大于-7℃时,室内平均温度可达到20℃以上,系统节能性较好;蓄热水箱的加入会影响运行初期机组的稳定性,但可使室温得到快速提升并提高系统的制热性能,在相同运行条件下,蓄热水箱-热泵混合供暖期间室内平均温度为24.61℃,系统COPs为2.01,较蓄热水箱与空气源热泵交替供暖及单一空气源热泵供暖模式分别提高6.90%、21.08%,供暖效果最佳。     

太阳能供暖与制蒸馏水综合应用技术

在非供暖期,为了维护太阳能供暖系统的完好,避免太阳能集热器因干烧导致损坏,提出了一种太阳能供暖与制蒸馏水综合应用技术方案。通过对太阳能集热供暖设施进行技术改造,使太阳能集热装置在冬季用于建筑供暖,在非供暖期用于制蒸馏水,提高了太阳能集热系统的利用率。     

农村太阳能供暖住宅

以农村住宅进行太阳能供暖模拟试验得出的结论为依据,提出农村太阳能供暖住宅的设计方案:①提高农村住宅的保温隔热性能.降低建筑能耗;②要创新太阳能供暖设备,提高供暖系统的热效率;③实施太阳能与建筑一体化,使住宅热负荷与太阳能集热器的有用热量相匹配,实现农村住宅的主房间室内温度常年保持在16℃～28℃之间波动,居住舒适.     

晋北地区村镇住宅建筑供暖系统优化及经济性研究

以晋北地区某村镇住宅建筑为例，对太阳能与电锅炉供暖系统进行设计方案优化及经济性研究。根据晋北地区气候特征，分析村镇住宅建筑负荷特性；采用模拟研究方法，分别对太阳能系统供暖、电锅炉系统供暖以及太阳能与电锅炉耦合系统供暖进行建筑能耗模拟；针对面积为60 m²、100 m²、200 m²村镇住宅建筑，考虑不同热源承担的建筑负荷比例、供热系统初投资及运行费用，优化不同面积村镇建筑的供暖模式以及不同热源承担的负荷占比。结果显示：太阳能系统初期投资高，电锅炉系统运行费用高。长期运行时，太阳能供暖系统的经济性优于电锅炉供暖系统。太阳能供暖系统与电锅炉供暖系统单独运行时，太阳能供暖系统不能很好地满足供暖条件，而电锅炉供暖系统运行费用较高；太阳能+电锅炉供暖系统的太阳能和电锅炉的供暖占比分别为50%时，前期投资和系统运行费用比较经济。     

太阳能直接供暖运行工况分析

太阳能是一种清洁能源,在提倡环境保护和能源节约的今天,太阳能技术得到了迅速的发展。课题组开发了太阳能热泵供热系统,进行了太阳能直接供暖工况的运行,测试期间,日间太阳辐射量的平均值为47.71kWh,日间集热量的平均值为22.41kWh;系统日耗电量在8.46~8.52kWh之间变化,平均值为8.49kWh。系统平均效率为0.35,测试期间室内温度满足要求。     

Wall-particles heat transfer in rotating heat exchangers

The wall-particles heat transfer coefficient has been measured in small-scale rotary drum heat exchangers. Experiments have been conducted with nine granular materials of different nature, with particle diameters ranging from 194 μm to 4mm. The effects of rotational speed (1–40 rev min⁻¹), filling degree (4–17%) and drum diameter (0.25 and 0.485 m) have been investigated. The experimental data have been correlated by a semi-empirical relationship, that includes a contact resistance at the wall, the heat capacity of the particles immediately adjacent to the wall and the heat penetration resistance of the bulk of the particle bed. The contact resistance is shown to be due to the roughness of the particles. A mean roughness height of 12 μm provides a good fit to the measured coefficients.     

A review of the applications of heat pipe heat exchangers for heat recovery

The waste heat recovery by heat pipes is accepted as an excellent way of saving energy and preventing global warming. This paper is a literature review of the application of heat pipes heat exchangers for the heat recovery that is focused on the energy saving and the enhanced effectiveness of the conventional heat pipe (CHP), two-phase closed thermosyphon (TPCT) and oscillating heat pipe (OHP) heat exchangers. The relevant papers were allocated into three main categories, and the experimental studies were summarized. These research papers were analyzed to support future works. Finally, the parameters of effectiveness of the CHP, TPCT and OHP heat exchangers were described. This review article provides additional information for the design of heat pipe heat exchangers with optimum conditions in the heat recovery system.     

Internal heat generation in a discrete heat source: Conjugate heat transfer analysis

In the present work, we conduct an asymptotic and numerical analysis for the cooling process of a discrete heat source, which is placed in a rectangular-channel laminar cooling flow. In our physical model, the heated strip is embedded in a substrate, generating continuously a uniform volumetric heat rate. We assume that this heat-generation mechanism is due to an electrical current in the heat source. Hence, heat losses to the cooling fluid and to the substrate material during this process are presented. The governing equations of the cooling flow and the participating solid are reduced to an integro-differential equation that predicts the temperature variations of the heat source. We show that the conjugate heat transfer process is controlled by a conjugate nondimensional parameter, here denoted by α, which determines the basic heat transfer regimes between the cooling flow and the discrete heat source.     

Waste heat recovery using heat pipe heat exchanger for heating automobile using exhaust gas

The feasibility of using heat pipe heat exchangers for heating applying automotive exhaust gas is studied and the calculation method is developed. Practical heat pipe heat exchanger is set up for heating HS663, a large bus. Simple experiments are carried out to examine the performance of the heat exchanger. It is shown that the experimental results, which indicate the benefit of exhaust gas heating, are in good agreement with numerical results.     

地源热泵的套管式地下换热器传热研究

地源热泵是一种节能、对环境无害的绿色空调设备,可成为下个世纪冷暖技术的核心,采用能量平衡,建立了地下浅埋套管式换热器传热平衡式,进行求解,并分析了影响传热的各关联因子,提出了需研究的强化地下换热的措施,根据求解结果,给出了相应的函数关系图。对实验设计和工程实践有一定的指导作用。     

Upgrading heat by a reversed absorption heat pump

Analysis of a reversed absorption heat pump's performance for upgrading low temperature waste-heat from industrial processes and solar heat from a flat-plate solar collector has been carried out. In the case of upgrading waste-heat, the ratio of output to input heat decreases as the temperature at which the output heat is needed increases. For water heating, the performance of the conventional solar water heating system is better than that of the heat pump system because in the latter case, heat is rejected from the condenser.     

一种新颖简易的太阳能热动力转换装置--明托热机

明托热机(Minto Engine),俗称明托转轮,它 是通过液体活塞在转轮中不停地变换位置,产生不 同的动力矩,从而驱动转轮旋转的机器。明托热机 最早于1975年被维利·明托(Wally Minto)发明。 早期的明托热机结构十分简单,效率也很低,但由 于它能将低品位热能转变成高品位的动力。因而一 下子吸引了许多科学家的注意。之后,许多学者对 明托热机进行了研究,提出了许多改进的方向和应 用领域,推动了明托热机的发展。     

Frosting of heat pump with heat recovery facility

This paper aims to prolong the heat pump frost time and reduce its growth with heat recovery facility, which should mix the exhausted indoor and outdoor air before entering the evaporator. An ideal mathematic model is developed for heat transfer, frost generation and airside pressure drop. The properties of the mixture would be obtained by solving the mass and energy conservation equations. A parametric analysis is performed to investigate the effects of air inlet temperature, relative humidity and air mass flow rate on total heat transfer coefficient, frost thickness and airside pressure drop, respectively. The results show that rationalizing the ratio of indoor and outdoor air could prolong frosting time and reduce the frost thickness greatly. The total heat transfer coefficient, frost thickness and airside pressure drop increase monotonically with time going, but are not proportional. Decreasing the mixture inlet air temperature and relative humidity could essentially reduce frost growth on the tube surfaces. This can also be observed when increasing the air mass flow rate.     

Forced convection heat transfer in microchannel heat sinks

This paper presents an analysis of forced convection heat transfer in microchannel heat sinks for electronic system cooling. In view of the small dimensions of the microstructures, the microchannel is modeled as a fluid-saturated porous medium. Numerical solutions are obtained based on the Forchheimer–Brinkman-extended Darcy equation for the fluid flow and the two-equation model for heat transfer between the solid and fluid phases. The velocity field in the microchannel is first solved by a finite-difference scheme, and then the energy equations governing the solid and fluid phases are solved simultaneously for the temperature distributions. Also, analytical expressions for the velocity and temperature profiles are presented for a simpler flow model, i.e., the Brinkman-extended Darcy model. This work attempts to perform a systematic study on the effects of major parameters on the flow and heat transfer characteristics of forced convection in the microchannel heat sink. The governing parameters of engineering importance include the channel aspect ratio (α_s), inertial force parameter (Γ), porosity (ε), and the effective thermal conductivity ratio (k_r). The velocity profiles of the fluid in the microchannel, the temperature distributions of the solid and fluid phases, and the overall Nusselt number are illustrated for various values of the problem parameters. It is found that the fluid inertia force alters noticeably the dimensionless velocity distribution and the fluid temperature distribution, while the solid temperature distribution is almost insensitive to the fluid inertia. Moreover, the overall Nusselt number increases with increasing the values of α_s and ε, while it decreases with increasing k_r.