夏热冬冷地区多能源互补的冷热沼气联供系统性能研究

It is significant that utilize renewable energy to meet the increased building energy consumption in hot-summer and cold-winter region, multiple-energy complementary is an effective way which can meet multiple energy demands and supply energy stably. Thus, based on the distribution characteristics of solar energy, biomass energy and air thermal energy in this region, a combined energy system for cooling, heating and biogas (CCHB) have been proposed and developed with the integration of low temperature solar collectors, thermostat biogas digester, and heat-source tower heat pump, according to the energy utilization principle of “temperature counterpart and cascade utilization”. Then, the technical-economic performance and stability under extreme weather conditions of the CCHB, the principle of energy transfer and conversion among the units of the system and between the system and environment, and the mechanism of multiple-renewable energy complementary would be studied by the combined methods of theoretical analysis, numerical simulation and field experimental study, later, the quantitative relationship between the energy supplied and consumed of the CCHB and the integrated approach, operation mode of the CCHB, and environmental factors like air temperature and humidity, solar radiation, could be revealed, lastly, the optimal integrated approach and operation mode of the CCHB would be achieved, which can make the technical-economic performance best based upon the stably energy supply under the weather conditions of the hot summer and cold winter region. The results of the project will scientifically guide the popularization of clean energy and improving of human and natural environment, besides, the results will also enrich the theoretical system of relative research fields.

利用可再生能源满足夏热冬冷地区激增的建筑能耗意义重大，多能互补是满足多层次用能需求和实现稳定高效供能的有效途径。为此，结合该地区太阳能、生物质能和空气热能的分布特征，本项目将根据“温度对口，梯级利用”的能量利用原则，构建集成了低温太阳能集热器、恒温沼气发生器和能源塔热泵，能稳定满足该地区农村居民夏季制冷、冬季采暖、全年生活热水和炊事燃气需求的供能系统，拟运用理论分析、数值模拟与实验研究相结合的方法，研究系统的技术经济性和极端条件下的供能稳定性、系统内部及与环境之间的能量传递与转换规律、多种可再生能源的互补机理，揭示系统集成方式、运行策略，以及空气温湿度、太阳辐射、日照时间等环境因素对系统供能和自身耗能影响的定量关系，最终获得夏热冬冷地区气象条件下使系统性能达到最优的集成方案和运行策略。本项目的研究结果可对该地区农村的清洁能源推广应用、人居和自然环境改善提供科学指导，并丰富相关的理论体系。

本项目研究了夏热冬冷地区多能源互补的供能系统的制热性能。1.当环境温度在5.1~5.4℃，相对湿度在92.1~94.5%内变化时，供热温度高于46.7℃，系统制热量高于13kW，热泵机组COP平均为2.86；当环境温度在2.5~0.1℃，相对湿度80.4~89.5%内变化时，供热温度高于43℃，系统制热量随环境温度的降低而减小，在最低环境温度时制热量为11.4kW，热泵机组COP最低为2.64。2.实验研究了冬季制热工况下闭式热源塔运行参数对热源塔吸热量和热泵系统性能的影响，结果表明：防冻溶液循环泵频率降低使防冻溶液流出蒸发器的温度减小，但防冻溶液进出热源塔的温差增大，防冻溶液流量过高或过低都会降低闭式热源塔的吸热量；风机频率降低导致防冻溶液进出热源塔的温度和温差降低，不利于热源塔从空气中吸热和系统制热；循环泵和风机频率降低至15Hz和10Hz时，均出现机组蒸发温度降低而排气温度过高的现象，不利于机组的安全运行；系统最高制热量超过13kW，机组COP平均值最高可达2.94，系统SEER平均值最高可达2.15，但三者不同时出现。3.实验研究了太阳能辅助闭式热源塔热泵系统的制热性能，初步分析了太阳热能与空气热能的互补机理。研究结果表明：系统制热量范围为12.1~15.2kW，热泵机组COP范围为2.3~3.5，系统SEER范围为1.5~2.4，供热温度高于41℃；冷却水温度对压缩机耗电量的影响程度大于防冻溶液温度，冷却水平均温度每升高1℃，压缩要耗电量增加98.1W，而防冻溶液平均温度每升高1℃，压缩机耗电量减小9.5W；太阳能辅助热源塔热泵制热模式下，热泵机组通过改变防冻溶液与空气和集热工质换热温差的方法来改变防冻溶液从空气和集热水箱中的吸热量，以实现空气热能与太阳热能的互补。实际应用中应在保证热舒适要求的情况下避免供热温度过高以减小压缩机耗电；集热水箱温度较高时可通过降低风机频率减小风机耗电以提高系统SEER。