太阳能-热泵木材干燥系统

一干燥系统原理太阳能 热泵木材干燥系统主要由四部分组成 ,即太阳能加热系统、干燥室、热泵除湿机（干燥机）和微机监测与控制系统。木材干燥系统的供热与湿空气的排湿由太阳能加热系统和热泵除湿机二者配合起来完成。二者既可单独使用 ,也可联合使用。如果天气晴好 ,气温高 ,则可单独使用太阳能加热系统 ;天气不好或夜间 ,即可由干燥机来承担木材干燥的供热与除湿任务。太阳集热器为拼装式平板型空气集热器 ,它采取阵列形式布置 ,可以根据需要拼装成任何采光面积 ,安装维修都很方便 ;干燥室为金属型结构 ,外砌砖墙 ,内贴铝板 ,中间衬以保…     

太阳能-空气源热泵联合干燥系统设计及干燥枸杞的实验研究

为缩短枸杞干燥时间,提高干制枸杞的质量,减少能源消耗,本文提出了一种新型太阳能–空气源热泵联合干燥系统。该系统主要由太阳能集热器和空气源热泵机组等设备组成,可以实现太阳能单独干燥、热泵单独干燥和太阳能–空气源热泵联合干燥三种工作模式。本文根据枸杞的干燥特性,分段设定最佳的干燥温度,进行了热泵单独运行和太阳能–热泵联合运行两种工作模式下干燥枸杞的对比实验。结果表明,干燥50 kg枸杞,太阳能–热泵联合运行比热泵单独运行节省了2.9 kW?h电能,若同时除去系统本身的耗能,节省的电能占热泵单独运行耗电量的29.5%。同时,与太阳能单独干燥相比,太阳能–热泵联合干燥具有较高的除湿能耗比,两者最大差值为0.71 kg/(kW?h)。本文提出的太阳能–热泵联合干燥系统具有提高干燥产品的品质、缩短干燥时间和节约干燥成本等优点,适宜推广。     

闭式热源塔热泵系统制热性能实验研究

为了探究利用热源塔热泵系统对陕南地区以及气候相近地区进行冬季供暖的可行性,设计了一套小型闭式热源塔热泵系统,并在冬季条件下,对该系统的制热性能进行了实验研究。分析结果表明:当环境温度为5.1～5.4℃,环境相对湿度为92.1%～94.5%时,闭式热源塔热泵系统的供热温度高于46.7℃,制热功率大于13kW,热泵机组COP的平均值为2.86;当环境温度为2.5～0.1℃,环境相对湿度为80.4%～89.5%时,闭式热源塔热泵的供热温度高于43℃,制热功率随着环境温度的降低而减小;当环境温度达到最低值(0.1℃)时,制热功率为11.4 kW,热泵机组COP的最低值为2.64,这表明热源塔热泵系统可以应用于陕南地区以及其他气候相近地区。     

基于中温热泵的消防水带干燥装置性能研究北大核心CSCD

为研究消防水带的干燥特性曲线,实现低能耗、快速干燥的目的,文章研发了以R134A为制冷剂的中温热泵消防水带干燥装置。通过实验方法分析消防水带干燥特性,并对该中温热泵消防水带干燥装置的性能开展研究,对比不同送风温度、风速下,系统性能系数(COP)、制热量、干燥时间、干燥过程耗电量、单位能耗除湿量(SMER)、单位时间除湿量(MER)的变化规律。结果表明,在一定范围内,随着送风温度的增加,COP降低、SMER和MER均升高。风速不变,送风温度为70℃时,干燥性能最优,SMER为0.427 kg/(kW·h),MER为1.584 kg/h,比送风温度为40℃时提高了10.9%和62.1%。送风温度不变,风速为4 m/s时,干燥效果最好,SMER为0.543 kg/(kW·h),MER为1.137 kg/h,比风速为2 m/s时提高了20.4%和50.2%。送风温度为50℃时,比消防水带吹干机节能约52%。     

新型压缩吸收耦合的太阳能热泵系统实验研究

提出一种太阳能吸收子系统过冷压缩循环的新型压缩吸收耦合热泵系统,由压缩子系统、吸收子系统和太阳能集热子系统3部分组成;在夏冬两季均可使用。针对该新型太阳能热泵在恒定工况下的制冷、制热性能进行稳态实验研究。实验结果显示,夏季制冷时,在冷冻水进口温度12℃,冷凝器出口制冷剂温度50℃时,新型太阳能热泵系统的制冷最低COP为4.02,与同工况的常规压缩热泵相比,制冷COP提高13.88%;冬季制热时,存在COP的极值转变温度。在实验环境温度为16℃,冷凝器热水出口温度59℃时,新型耦合系统最小的制热COP为5.44,与同工况常规压缩热泵相比,制热COP提高11.52%。显示了新型系统的巨大优势,具有良好的应用前景。     

太阳能联合空气源热泵系统温室供热实验研究

在西安地区一座日光温室中采用太阳能联合空气源热泵供热系统进行对比实验研究,比较太阳能联合空气源热泵系统改善温室内的温度、湿度及土壤温度等环境因素,分析评价太阳能联合空气源热泵系统在日光温室冬季应用的效果。实验结果表明:太阳能联合空气源热泵供热系统不仅可明显提高温室内的空气温度和土壤温度,还可有效降低温室内的湿度;在实验天气条件下,热泵单独供热时,系统的COP为2.2~3.5;太阳能联合空气源热泵供热时,系统的COP为2.9~6.0;相比于阴天工况,晴天条件下,太阳能蓄热供热时间较长,热泵补充供热时间缩短,系统COP较高。     

太阳能热泵联合系统的枸杞干燥特性与能耗分析

为降低碳排放,利用太阳能集热器与空气源热泵联合干燥代替传统的燃煤热风炉干燥。通过对比太阳能热泵联合干燥和热泵单独干燥试验,研究太阳能热泵系统除湿特性。同时,进行太阳能空气集热器辅助空气源热泵的枸杞干燥试验,验证其可行性。在相同干燥温度设定下,太阳能热泵联合干燥相比热泵单独干燥节电了28.8%,高干燥负荷试验组较中等干燥负荷试验组相比节电15%。与传统热风炉烘干房干燥相比,每吨枸杞干燥节约成本448元,同时节约标准煤121.14 kg,可减少CO2排放量317.39 kg。     

多能互补清洁供暖系统特性分析

为加速能源低碳转型,本文提出了一种基于太阳能、风能和地热能3类可再生能源多能互补的清洁耦合供暖方案,即在利用地热能供热的同时,将太阳能和风能联合其中实现辅助供热,从而突破太阳能与风能的不稳定性及间歇性等缺点,达到3类能源的合理配置效果。首先,在EBSILON软件中搭建了集热、储热、换热各能量转换与输运的热力模型,选定郑州典型供暖季的气象、地热等自然资源条件作为初始约束,研究了太阳能光热换热效率、供暖量及地热单元供暖输出等关键指标的变化规律。结果表明：光热转换效率集中分布在45%～60%;辐照较弱时,太阳能主要依靠储热装置放热维持机组热平衡,其最低供热谷值为27.268 kW;随着外界辐射能力的增强,系统供热量最大可达40.311 kW;在夜晚时段,地热机组供热量出力占主导,输出负荷最大达165.556 kW;相较于日照条件较好的白天,经太阳能预加热的回水温度有所升高,致使地热机组日间供热量相对减小,最小供热量为163.637 kW;当地热温度梯度上升5℃时,该机组供热量平均增高6.548 kW;风能利用单元伴随着机组负荷与外部风资源的波动,灵活地满足后端热泵机组处电压缩机用能需求,确保...     

直膨式太阳能热泵集热/蒸发器性能优化及其低温适应性研究

对直膨式太阳能热泵系统的集热/蒸发器结构进行优化,设计由六边形与四边形单元组合的流道结构,并进行仿真与实验研究。在上海地区,冬季工况下,将水温从10℃加热到50℃,系统COP可达到4.5;夏季工况下,将水温从30℃加热到55℃,系统COP可达到6.60。在此基础上,针对严寒地区冬季运行,研究了与喷气增焓循环耦合的低温型直膨式太阳能热泵系统。在环境温度为-10℃时,系统COP可达到3.79;环境温度为-20℃时,系统COP可达到3.69。依据实验与仿真数据,运用全生命周期经济性分析方法,以当量热价(LCoH)为评价指标,为太阳能热泵采暖经济性分析提供计算方法和理论依据。     

太阳能与土壤源耦合供暖系统的实验研究

在分析太阳能、土壤源热泵及联合供热特点的基础上,研究了太阳能热泵独立系统、土壤源耦合热泵系统运行模式的制热性能和节能效果,建立了太阳能蓄能-热泵耦合热泵系统的供暖模式及优化模型.通过采暖季初期的太阳能蓄能、供暖,土壤源热泵独立供暖及太阳能-土壤源耦合热泵供热的实验研究,验证了太阳能-土壤源耦合热泵供暖模式的可行性和经济...     

太阳辐射强度和温度对增强型冷却塔换热性能影响的研究

太阳能增强型自然通风冷却塔(SENDDCT)作为一种新型空气冷却系统,可利用太阳能提高自然通风冷却塔的效率。利用FLUENT软件建立太阳能增强型冷却塔的三维模型,研究太阳辐射强度和环境温度对其性能的影响;同时设计并搭建太阳能增强型冷却塔的实验系统,在实际天气条件下研究太阳辐射强度对其换热性能的影响。模拟结果表明太阳辐射强度一定时,通过换热器的空气流速以及换热率都会随着环境温度升高而降低。太阳辐射强度为500 W时,环境温度由10℃升到40℃,换热率由1.106 kW下降到0.281 kW。实验结果表明有辐射时冷却塔入口处的平均空气温度要比无辐射时的高5℃;实验期间无辐射时的平均换热率为0.682 kW,有辐射时的平均换热率为0.794 kW,即利用太阳能将平均换热率提高了0.112 kW。     

A solar-assisted heat pump system for heating and cooling residences

A significant impact of solar energy applications on the total energy demand requires systems or devices which can be retrofitted to existing energy users. The all-electric residence unit, which includes about 10 per cent of all such units in the U.S.A. and constitutes over half of those completed in 1973, seems particularly suited to a solar modification. It is proposed that heating and cooling of the all-electric residence unit be accomplished by using a solar-assisted heat-pump system. The proposed system makes use of a conventional air-conditioning unit which would be modified by fitting controls to reverse the flow of refrigerant for the heating mode and by changing the outdoor heat exchanger from refrigerant-to-air to refrigerant-to-water. In addition, there would be provided a solar collector and two insulated water-storage tanks. Water from one tank would be circulated through the refrigerant-to-water heat exchanger when needed and then returned to the other tank, so that essentially a source of heat of constant temperature would be maintained, thus decreasing the temperature interval for the heat pump and thereby saving energy. In the cooling mode the stored water would be cooled by exposure of the solar collector to the night sky to decrease the temperature interval for the heat pump, thereby reducing energy consumption. Calculations were made for an existing residence unit for which the total energy input is known and to which the proposed solar-assisted heat-pump system is applied. An estimated cost of equipment and of its operation is compared with the cost of owning and operating fuel and electrically heated systems. It is concluded that the solar-assisted heat-pump system with current fuel prices can provide immediate economic benefit over the all-electric home and is possibly on par with residences using fuel oil or liquefied petroleum gas, but it yields higher cost over systems using natural gas. The effect of a two-phase expander to replace the expansion valve in the refrigerant circuit has been theoretically investigated. It shows a significant energy saving worthy of further economic and practical consideration.     

固-固相变蓄热材料在太阳能高温空气集热系统中的应用研究

为利用太阳能获得稳定持续的高温空气工质,除了有效集热外,还需要解决因太阳辐射强度变化导致输出工质温度波动的问题。在性能优良的太阳能集热系统中采用蓄热技术是解决此问题的有效途径。根据给定的设计目标,研究将固-固相变蓄热材料季戊四醇应用到太阳能集热蓄热一体化的实验装置中。实验结果表明:按集热蓄热一体化思路设计的实验装置,集热单元能够输出最高温度超过220℃的高温空气,蓄热单元能够将高温空气的温度稳定在蓄热材料的相变温度附近。并且随着蓄热管级数的增加,空气出口温度稳定的时间就越长,为利用太阳能获得稳定持续的高温热媒工质奠定了基础。     

相变贮热在热泵干燥机组中的应用研究

热泵干燥既能节约能量又可提高产品的质量,当干燥温度满足干燥要求后,热泵干燥机组往往通过排放掉一部分热量来维持干燥温度的稳定,这样降低了热泵干燥的能源利用效率,利用相变材料相变热效应,回收这部分能量,而且又在机组需要热量时将贮存的能量释放给干燥空气,实验结果证明了相变材料在热泵干燥机组中的应用具有明显的节能潜力。     

不同地区住宅能耗与太阳能吸收式空调系统匹配性分析与模拟研究

为了满足农村住宅清洁用能的需求,多种形式的能源系统逐渐开始应用于广大的农村地区。随着太阳能集热器集热效率的提高,热驱动机组各项性能不断改善,这样有利于太阳能吸收式空调系统在农村地区的应用。为了研究太阳能吸收式空调系统与农村住宅全年能耗的匹配问题,文章首先建立了DeST住宅模型,然后利用TRNSYS软件建立了太阳能吸收式空调系统模型,最后根据模拟结果对国内不同气候区内农村住宅供热季、供冷季的平均热负荷值,以及全年的能耗进行分析。此外,文章还分析了典型日太阳能吸收式空调系统的运行策略与效果。分析结果表明:在无辅助热源的条件下,太阳能集热器的集热温度会大于80℃,满足空调机组的热驱动温度,因此可以作为太阳能吸收式空调系统的的热源;当启动温度为85℃时,空调机组的制冷量可以达到8 kW,性能系数COP为0.733。     

Energy savings in indoor swimming-pools: comparison between different heat-recovery systems

In indoor swimming-pool facilities, the energy demand is large due to ventilation losses with the exhaust air. Since water is evaporated from the pool surface, the exhaust air has a high water content and specific enthalpy. Because of the low temperature, the heat from the evaporation is difficult to recover. In this paper, the energy demand for the conventional ventilation technique in indoor swimming pools is compared to two different heat-recovery techniques, the mechanical heat pump and the open absorption system. The mechanical heat-pump is the most widely used technique in Sweden today. The open absorption system is a new technique in this application. Calculations have been carried out on an hourly basis for the different techniques. Measurements from an absorption system pilot-plant installed in an indoor swimming pool in the northern part of Sweden have been used in the calculations. The results show that with the mechanical heat pump, the electrical input increases by 63 MWh/year and with the open absorption system 57 MWh/year. However, a mechanical heat-pump and an open absorption system decrease, the annual energy demand from 611 to 528 and 484 MWh respectively, which correspond to decreases of approximately 14 and 20% respectively. The electricity input will increase when using heat-recovery techniques. Changing the climate in the facility has also been investigated. An increased temperature decreases the energy demand when using the conventional ventilation technique. However, when either the mechanical heat-pump or the open absorption system is used, the energy demand is increased when the temperature is increased. Therefore increasing the temperature in the facility when using the conventional technique should be considered the first measure to reduce the energy demand.     

Cooling potential of ventilated PV façade and solar air heaters combined with a desiccant cooling machine

Thermal energy collected from a PV-solar air heating system is being used to provide cooling for the Mataro Library, near Barcelona. The system is designed to utilise surplus heat available from the ventilated PV facade and PV shed elements during the summer season to provide building cooling. A desiccant cooling machine was installed on the library roof with an additional solar air collector and connected to the existing ventilated PV façade and PV sheds. The desiccant cooling cycle is a novel open heat driven system that can be used to condition the air supplied to the building interior. Cooling power is supplied to the room space within the building by evaporative cooling of the fresh air supply, and the solar heat from the PV-solar air heating system provides the necessary regeneration air temperature for the desiccant machine. This paper describes the system and gives the main technical details. The cooling performance of the solar powered desiccant cooling system is evaluated by the detailed modelling of the complete cooling process. It is shown that air temperature level of the PV-solar air heating system of 70 °C or more can be efficiently used to regenerate the sorption wheel in the desiccant cooling machine. A solar fraction of 75% can be achieved by such an innovative system and the average COP of the cooling machine over the summer season is approximate 0.518.     

APPLICATION OF HEAT PUMP SYSTEMS FOR ENERGY CONSERVATION IN PAPER DRYING

Drying is one of the most energy intensive and common operations in the chemical and process industries. Scope for energy recovery is substantial, particularly from the latent heat of the exhaust moist air. Using real operating data from a major Swedish mill, optimal energy conservation strategies were investigated using different heat pump systems in paper drying. Simulation results are compared for compressor-driven and absorption heat pump systems. An absorption heat transformer was also investigated. A CH₃OH–LiBr double-lift cycle would have a low COP value due to the low temperature of the moist air stream and the restricted temperature of the cooling water available. A total of 30 MW thermal equivalent is currently needed in the mill at a temperature of 75°C for mixing-pits, district heating and a log store. Exhaust humid air at a temperature of 54°C from only three of the paper machines was used in this study. SHPUMP simulations revealed that installing a mechanical heat pump unit using HFC 134a would result in a recovery of 22 MW due to the temperature level of this application. On the other hand, 12 MW can be recovered with an absorption heat pump. To optimize the operating conditions, H₂O–NaOH was selected as the best of three based on exergy index criteria. Assuming a steam cost of 22 $/MW h and an electricity cost of 32 $/MW h, the pay-off periods would be 3·3 and 2·9 years for compressor-driven and absorption heat pump alternatives, respectively. © 1997 by John Wiley & Sons, Ltd.     

Solar heat pump systems for domestic hot water

Vapour compression heat pumps can upgrade ambient heat sources to match the desired heating load temperature. They can offer considerable increase in operational energy efficiency compared to current water heating systems. Solar heat pumps collect energy not only from solar radiation but also from the ambient air. They can operate even at night or in totally overcast conditions. Since the evaporator/collector operates at temperatures lower than ambient air temperature it does not need glazing or a selective coating to prevent losses. Currently, however, they are not used much at all in domestic or commercial water heating systems. In this paper comparison is made of a conventional solar hot water system, a conventional air source heat pump hot water system and a solar heat pump water heating system based on various capital city locations in Australia. A summary is given of specific electricity consumption, initial and operating costs, and greenhouse gas generation of the three systems dealt with in this paper. The ultimate choice of unit for a particular location will depend heavily on the solar radiation, climate and the local price paid for electricity to drive or boost the unit chosen.