PCM空气式太阳能干燥在茶叶加工中的应用

介绍了云南普洱市的某茶业公司PCM空气式太阳能一热泵联合干燥房建设及应用实例。普洱茶传统加工工艺采用燃煤蒸汽锅炉进行茶饼烘干处理,现进行技术改造,采用节能环保的PCM空气式太阳能热泵干燥系统代替现有的燃煤锅炉干燥系统。通过PCM空气式太阳能集热系统,将太阳能转换热能。以空气为换热介质与空气式太阳能集热器进行换热,通过循环风机直接将热风通入到烘房内提供物料干燥热量需求;当太阳能不足时,启动空气源热泵系统。对该工程的设计方案并及干燥系统工作原理进行了详细介绍,从干燥系统运行过程中采集数据进行分析计算,计算结果表明本干燥系统节能效果明显。这些数据对目前高效利用太阳能进行商业干燥设计参数的选取,以及太阳能干燥系统的优化设计具有重要借鉴意义。     

高压电场组合干燥技术的研究进展

针对目前干燥设备干燥效率不高、能耗较大的问题,分析了高压电场组合热风干燥和高压电场组合真空冷冻干燥,论述了一种新型干燥工艺——太阳能辅助高压电场干燥。该工艺利用高压电场实现高效干燥,再利用太阳能辅助来达到节能的目的。该设备由太阳能系统、控制系统、高压发生装置系统、干燥室系统四部分组成。介绍了高压电场在不同产品干燥中的利用,并结合太阳能利用对新型干燥工艺进行理论研究,同时介绍了设备局限性以及发展趋势。     

太阳能与热泵联合干燥茶叶的应用研究

为开发茶叶干燥新方法,利用太阳能集热与热泵联合干燥代替传统的干燥方式,采用相变蓄热和辅助热源保证干燥系统能够全天候工作。使用空气源热泵技术作为太阳能集热系统辅助热源和策略控制,达到节能高效目的。经干燥茶叶试验研究表明,采用相变蓄热太阳能与空气源热泵联合干燥,能够解决干燥系统能量供应的稳定性和经济性问题,整个联合干燥系统与燃煤烘箱干燥相比,节能36.7%~41.1%,节能减排效果显著。从茶叶的干燥特性试验中得出在50~60℃间,均可在8 h内达到所要求的含水率,干燥时间随干燥风温的升高而缩短,干燥后的茶叶质量等级相比同等条件下的传统干燥方式有所提高。     

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。     

寒冷地区某中学能源改造技术方案可行性分析

基于对寒冷地区某中学既有冷热源系统的调研资料,针对既有系统的现状问题,从负荷预测、改造方案设计、改造效益分析三个方面对现有冷热源系统进行节能改造。通过采用太阳能-地源热泵系统改造,改造后每年可以节约1097.11吨标准煤,减少CO2排放2735.1t,可节省运行费用为184.35万元。预计7a回收改造投资,真正实现节能减排的目标。     

直接空冷火电站废热再利用系统

本文受到太阳能烟囱发电技术的启发,提出用直接空冷火电站乏汽放出的潜热替代太阳能烟囱发电中不稳定的太阳能,不仅弥补了太阳能烟囱发电技术的不足,而且回收利用了直接空冷火电站中以往被浪费的乏汽潜热,进一步减少了火电站鼓风机的耗电量。以一台600 MW直接空冷火电机组为例,对系统的热力过程、阻力进行了理论分析。计算结果表明该系统每年可以回收电能2.89×108kW/h,可以产生约1.08亿元的经济效益;相当于每年可以节省标准煤10.43万t,减少排放CO2约27.32万t、SO2约886 t、NOx约772 t,经济效益和节能减排效果显著。     

真空管型太阳能空气干燥工程设计及性能分析

对应用于腊鸡腿干燥的真空管型太阳能空气集热器干燥工程进行设计和实验,理论设计值与实测值吻合较好,切实做到有利合理利用太阳能。按照国家标准对单元集热器性能进行测试,为参数设计及性能分析提供数据支撑。在非典型天气条件下实测系统性能并得到腊鸡腿的干燥特性曲线,分析认为系统具有较低的太阳依赖性及较强的稳定性。最后对企业采用的3种干燥系统的经济性能进行分析,结果显示采用太阳能干燥的系统具有较好的应用潜力及前景。     

新型环路热管太阳能热水系统节能减排评估

基于笔者前期理论及实验研究,运用实验验证的计算机程序,对一种新型环路热管太阳能热水系统在实际气候条件下的运行状况进行总体评估。研究发现,环路热管工作温度在很大程度上受太阳辐射强度影响;系统夏季热效率较高,性能系数较低。通过与传统太阳能热水系统进行比较分析,得出该系统相对于传统系统的节能减排效果为年节煤量0.040t、CO2减排量0.166t。     

蜜枣太阳能对流干燥最佳工况的试验研究

以蜜枣为干燥对象进行了太阳能对流干燥试验,建立了干燥数学模型;以能耗为优化目标得到了蜜枣太阳能对流干燥的最佳工况,并与蜜枣纯对流干燥的能耗进行了对比,对比结果表明太阳能对流干燥比纯对流干燥有明显的节能效果。     

污泥的太阳能干燥实验研究

采用自行设计制造的混合型污泥太阳能干燥装置对污水处理厂机械脱水后含水率在80％左右的污泥进行干燥。通过实验研究探索了利用混合型太阳能干燥器干燥污泥的可行性及污泥的干燥特性，并对污泥在干燥过程中外形发生变化的规律及其与干燥过程的关系作了描述，研究结果表明污泥形变、空气参数及太阳辐射强度是影响污泥干燥过程的主要因素，对太阳能污泥干燥的工业化生产具有参考价值。     

中低温热源干燥系统的设计及试验

为解决工农业干燥过程中存在的干燥效率低、能耗高等问题,同时充分利用生产过程中产生的中低品位热能,设计了一种可控温湿度的中低温热源干燥系统,干燥系统由加热系统、排湿换气系统、温湿度控制系统和干燥室组成。介绍了其干燥工艺,分析了其运行性能和能耗情况,通过试验数据分析发现该干燥系统气流温度和速度分布均匀、能耗低,系统在整个干燥过程中的干燥速率为0.122 kg/(kg∙h),整个过程的能耗因子为391.2 kJ/kg。系统适用于以地热能和工业余热等中低温热能为热源的工农业干燥过程。     

Thermodynamic method for designing dryers operated by flat-plate solar collectors

In this work a thermal performance analysis of the solar drying process is presented. It describes semi-empirical models for the thermal characterization of an experimental indirect solar dryer device. A procedure for designing drying equipment, which takes into account the varying operating conditions given by the variations of the environmental conditions is also presented. On the other hand, a simplified method to design solar collectors based on the determination of minimum entropy generation during the thermal conversion of solar energy, is described. Finally, the results of the preliminary design of the solar dryer are presented using the thermal analysis procedure and the method derived from the Second law of thermodynamics.     

LiBr-H_2O太阳能吸收式热泵海参干燥系统应用分析

提出以LiBr-H2O为工质对的太阳能吸收式热泵海参干燥系统,介绍此系统的组成及工作流程。LiBr-H2O太阳能吸收式热泵应用于干燥过程可以降低能耗,绿色环保。对其应用前景进行分析,同时提出该系统在推广应用方面的限制因素,对太阳能吸收式热泵海参干燥装置设计及推广具有参考价值。     

A solar assisted heat pump drying system for grain in-store drying

For grain in-store drying, a solar assisted drying process has been developed, which consists of a set including a solar-assisted heat pump, a ventilation system, a grain stirrer, etc. In this way, low power consumption, short cycle time and water content uniformity can be achieved in comparison with the conventional method. A solar-assisted heat pump drying system has been designed and manufactured for a practical granary, and the energy consumption performance of the unit is analyzed. The analysis result shows that the solar fraction of the unit is higher than 20%, the coefficient of performance about system (COPS) is 5.19, and the specific moisture extraction rate (SMER) can reach 3.05 kg/kWh.     

A solar assisted heat pump drying system for grain in-store drying

For grain in-store drying, a solar assisted drying process has been developed, which consists of a set including a solar-assisted heat pump, a ventilation system, a grain stirrer, etc. In this way, low power consumption, short cycle time and water content uniformity can be achieved in comparison with the conventional method. A solar-assisted heat pump drying system has been designed and manufactured for a practical granary, and the energy consumption performance of the unit is analyzed. The analysis result shows that the solar fraction of the unit is higher than 20%, the coefficient of performance about system (COP_S) is 5.19, and the specific moisture extraction rate (SMER) can reach 3.05 kg/kWh.     

Modeling, design and thermal performance of a BIPV/T system thermally coupled with a ventilated concrete slab in a low energy solar house: Part 1, BIPV/T system and house energy concept

This paper is the first of two papers that describe the modeling, design, and performance assessment based on monitored data of a building-integrated photovoltaic-thermal (BIPV/T) system thermally coupled with a ventilated concrete slab (VCS) in a prefabricated, two-storey detached, low energy solar house. This house, with a design goal of near net-zero annual energy consumption, was constructed in 2007 in Eastman, Québec, Canada - a cold climate area. Several novel solar technologies are integrated into the house and with passive solar design to reach this goal. An air-based open-loop BIPV/T system produces electricity and collects heat simultaneously. Building-integrated thermal mass is utilized both in passive and active forms. Distributed thermal mass in the direct gain area and relatively large south facing triple-glazed windows (about 9% of floor area) are employed to collect and store passive solar gains. An active thermal energy storage system (TES) stores part of the collected thermal energy from the BIPV/T system, thus reducing the energy consumption of the house ground source heat pump heating system. This paper focuses on the BIPV/T system and the integrated energy concept of the house. Monitored data indicate that the BIPV/T system has a typical efficiency of about 20% for thermal energy collection, and the annual space heating energy consumption of the house is about 5% of the national average. A thermal model of the BIPV/T system suitable for preliminary design and control of the airflow is developed and verified with monitored data.     

Energy simulation modeling and savings analysis of load sharing between house and office

This paper presents the potential benefits of the thermal load sharing between the two different building types such as residential house and commercial office building through the process of energy simulation modeling. Both the house and office simulation models have the same geometries with the conditioned spaces of 200 m² each for the weather conditions of Seoul, South Korea. This study shows and analyzes the thermal energy demand and consumption results simulated from the four different scenarios using the EnergyPlus V6.0 thermal simulation program; i.e., Case-1) a house with conventional heating and cooling systems, Case-2) an office with conventional heating and cooling systems, and Case-3) a simple sum of the two cases (i.g., Case-2 + Case-3), and Case-4) a load sharing model that provides heating and cooling to both the house and the office using combined HVAC systems. This paper evaluates the thermal energy consumption patterns and potential benefits of the load sharing system compared to the conventional systems. The optimal system configurations of the load sharing systems are proposed. In conclusion, this paper discusses the potential issues and challenges for implementing the load sharing systems as well as the possible solutions for these issues.     

Investigation of photovoltaic-hydrogen power system for a real house in Turkey: Hydrogen blending to natural gas effects on system design

In the study, the effects of hydrogen mixing studies at the rate of 20% to the natural gas system which is an ongoing study in Turkey, on the photovoltaic system (PV) is investigated using a real house consumption. Providing the annual electrical energy consumption (1936,83  kWh) and 20% of natural gas consumption (62,4 m³) of a real house with hydrogen is included in the study. A PV-hydrogen system is theoretically investigated to provide the energy required for hydrogen production from solar panels. Hydrogen blending effects on PV size, capacity usage, and carbon footprint are analyzed. Thus, the contribution was also made to the “green hydrogen” works and reduction of the carbon footprint of the house. It was found that the required hydrogen for electricity can be provided 52,5 m² solar panel area and 14,28% increase in this area and installed power can provide an amount of hydrogen that need for 20% hydrogen blending to the natural gas system. The overall system capacity usage decreased when the system is used for 20% hydrogen blending to the natural gas system. The carbon footprint of the house was decreased by 67,5%. If the hydrogen has not been blended with 20% natural gas, this ratio would have been 59,2%.     

Use of desiccant dehumidification to improve energy utilization in air-conditioning systems in Beirut

Humidity and indoor moist surrounding affect air cleanliness and protects harmful microorganisms when relative humidity is above 70%. In humid climates, the humidity issues are a major contributor to energy inefficiency in HVAC devices. The use of liquid desiccant dehumidification systems of supply air is a viable alternative to reduce the latent heat load on the HVAC system and improve efficiency. Thermal energy, at a temperature as low as 40–50°C, required for the operation of a liquid desiccant hybrid air conditioner can be efficiently obtained using a flat-plate solar collector. In this work a model of a solar-operated liquid desiccant system (using calcium Chloride) for air dehumidification is developed. The system utilizes packed beds of counter flow between an air stream and a solution of liquid desiccant for air dehumidification and solution regeneration. The desiccant system model is integrated with a solar heat source for performance evaluation at a wide range of recorded ambient conditions for Beirut city. Standard mass and energy balances are performed on the various components of the system and a computer simulation program is developed for the integrated system analysis. The desiccant system of the current study replaces a 3 TR (10.56 kW) vapour compression unit for a typical house as low latent load application, and is part of a hybrid desiccant–vapour compression system for a high latent load application, namely a small restaurant with an estimated cooling load of 11.39 TR (40 kW), including reheat. The relevant parameters of the desiccant system are optimized at peak load, and it is found out that there is an important energy saving if the ratio of the air flow rate in the regenerator to that in the dehumidifier is about 0.3 to 0.4. The COP of the desiccant unit is 0.41 for the house, and 0.45 for the restaurant. The size of the vapor compression unit of the restaurant is reduced to 8 TR when supplemented by a desiccant system. The performance is studied of the desiccant system integrated with a solar collector system and an auxiliary natural gas heater to heat the regenerator. The transient simulation of the solar desiccant system is performed for the entire cooling season. The solar fraction for the house is equal to 0.25, 0.47, and 0.68 for a collector area of 28.72, 57.44, and 86.16 m², respectively. The solar fraction for the restaurant is 0.19, 0.38, and 0.54, for the same collector areas. The life cycle savings for the house run solely on desiccant system were positive only if natural gas is available at a cheap price. For the restaurant, the economic benefit of the desiccant system is positive, because the need for reheat in the vapor compression system is eliminated. For a gas price of 0.5638 $/kg, the payback period for the restaurant turned out to be immediate if the energy is supplied solely by natural gas, and 11 years if an 86.16 m² solar collector is implemented to reduce the fuel consumption. Copyright © 2003 John Wiley & Sons, Ltd.