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直膨式太阳能热泵热水器运行特性的实验研究 总被引:2,自引:0,他引:2
本文针对自行设计、建造的“直膨式太阳能热泵热水器”实验样机进行了春季运行工况下的实验研究,并对其运行特性进行了详尽的分析.实验结果表明,在环境温度均值20.6℃、太阳辐射强度均值954.59 W/m2的室外气象条件下,将150升水从13.4℃加热到50.5℃只需要94分钟,热泵供热性能系数达到6.61.即使在环境温度为17.1℃的雨夜天气,热泵性能系数仍能够达到3.11.通过对典型工况下太阳能集热板的集热效率和过热度进行分析发现,如果用电子膨胀阀取代热力膨胀阀对供液量进行实时调节,可以进一步提高热泵的性能系数和系统运行的稳定性. 相似文献
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本文在深入分析燃煤电站CO2捕获和汽水系统热平衡的基础上,提出一种新型燃煤发电-CO2捕获-供热一体化系统。该系统通过汽水流程、碳捕获流程及地暖供热流程的有效集成,实现了系统中、低温余热的高效利用,降低了碳捕获对电厂效率的影响。分析结果显示,本文提出的一体化系统,在CO2回收率90%时,供电效率可达31.32%,供电效率降低8.96%,而传统化学吸收法碳捕获电站效率惩罚普遍在10~12个百分点或更高。同时,该系统可供热350 MW,全厂(火用)效率达34.49%,全厂热效率高达55.88%;该系统以较少的能耗代价实现高效供电、供热与CO2减排,为燃煤发电机组碳减排提供了独特的学术思路与技术方案。 相似文献
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对于S-CO2燃煤发电系统,系统复杂难以横向比较,拆分法通过对循环流量分配,能够梳理循环回热过程并进行循环间的比较,应用循环拆分法有助于对复杂燃煤发电系统的性能进行分析。本文以再压缩循环(RC)为例,构建了集成冷却器热量回收(CHR)和烟气冷却器法(FGC)的S-CO2燃煤发电系统(RC+LFGC+CHR),论证了拆分法在分析燃煤发电系统中的优势。当主气参数为620?C/28 MPa时,应用拆分法分析,RC+FGC+CHR可等效为在热效率49.21%的RC基础上,叠加热效率为57.49%的子循环(SSC+LFGC+CHR),故RC+FGC+CHR效率(49.80%)高于RC(49.21%)。 相似文献
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1引言吸收压缩式(SC)热泵是一种适用于变温热源的高效复合式热泵系统,比常规压缩式热泵具有工作范围广,工作压力低以及较高COP值等特点。文献出对以R22-DMA为工质的SC热泵进行了实验研究。本文则对新型工质R22-DMA的热力学性质进行研究整理,给出计算二元系统的蒸汽压、烩、摘等的实用公式;并对以其为工质的一种新型SC热泵循环进行计算机模拟优化分析,给出了实际SC热泵在典型制冷工况下的制冷性能及其优化条件。2R22-DMA的热力学性质2.1汽波相平衡R22-DMA二元系统的汽液相平衡实验数据较缺乏,文献[2]给出部分温度… 相似文献
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温室覆盖材料的热学性质 总被引:1,自引:0,他引:1
结合理论与实验,本文对温室内常用的几种覆盖材料的热学性质进行了研究。通过实验测试了不同材料的全辐射透射率,在一些大型温室中进行了温室太阳辐射的实验研究。在实验的基础上,对温室内外的太阳辐射强度进行了模拟。应用传热学基本原理,在合理假设的基础上,对温室覆盖材料的传热系数进行了模拟。 相似文献
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蔬菜大棚种植对蔬菜供应发挥着重要的作用,蔬菜大棚棚龄会影响蔬菜的产量和质量。以不同棚龄(1年、10年和18年)的黄瓜为对象,利用漫反射傅里叶变换中红外光谱,通过解析黄瓜的光谱特征峰,探究棚龄对黄瓜品质的影响。研究表明,黄瓜的多糖和蛋白质组分在3个棚龄呈现先增加后降低的趋势,10年棚龄种植的黄瓜多糖和蛋白质组分显著高于1年和18年的黄瓜多糖和蛋白质组分。高的棚龄(即10年和18年)显著增加了黄瓜的木质素组分。木质素组分主要分布于黄瓜皮中,增加木质素组分会降低黄瓜的食用口感。另外,黄瓜中各有机组分的比值能综合反映不同棚龄下黄瓜的品质。18年棚龄的黄瓜多糖与蛋白质组分的比值以及多糖与木质素组分的比值低于1年和10年棚龄的黄瓜各有机组分的比值,表明1年和10年棚龄的黄瓜中碳水化合物和营养物质的比值更加均衡。通过分析黄瓜各有机组分以及黄瓜各有机组分比值随着黄瓜棚龄的变化,知悉黄瓜棚龄在10年以内时,对黄瓜品质提升具有促进作用,但更长的棚龄会抑制黄瓜品质。因此,综合考虑黄瓜的品质,建议黄瓜棚龄不宜太长。另外,通过分析棚龄对黄瓜叶片有机组分的影响,发现黄瓜叶片各组分与黄瓜各组分的变化趋势相似。线性相关分析指出黄瓜蛋白质和木质素组分分别与黄瓜叶片蛋白质和木质素组分显著正相关,表明黄瓜叶片在一定程度上能反映黄瓜的营养成分和黄瓜口感。利用红外光谱解析不同棚龄下表征黄瓜品质的有机组分,为蔬菜大棚管理以及提高蔬菜品质提供了科学依据。 相似文献
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《Current Applied Physics》2020,20(9):1073-1079
We study emissivity (ε)-dependent radiative heat transfer phenomena in remote and contact configurations. To demonstrate the emissivity-dependent radiative heating mode in a remote configuration, we fabricated miniature greenhouses covered with low (0.34)- and high-ε (0.86) polyethylene films and monitored temperatures on the floors, insides, and covers of the greenhouses during 24 h. The high-ε greenhouse yielded a 9-°C increase in floor temperature relative to the low-ε greenhouse at a one-sun solar irradiance because the high-ε film effectively trapped floor radiation. In contrast, the cover temperature remained lower in the high-ε greenhouse due to intensified radiation released from the high-ε film. This self-cooling effect was more evident when an emissive film was in physical contact with an object. While bare copper heated up to 55 °C, a high-ε film coated copper substrate was kept cooler by 4 and 2 °C compared with the bare and low-ε film coated copper samples, respectively. 相似文献
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Thermally driven heat pump systems play important roles in the utilization of low-grade thermal energy. In order to evaluate and compare the performances of three different constructions of thermally driven heat pump and heat transformer, the low-dissipation assumption has been adopted to establish the irreversible thermodynamic models of them in the present paper. By means of the proposed models, the heating loads, the coefficients of performance (COPs) and the optimal relations between them for various constructions are derived and discussed. The performances of different constructions are numerically assessed. More importantly, according to the results obtained, the upper and lower bounds of the COP at maximum heating load for different constructions are generated and compared by the introduction of a parameter measuring the deviation from the reversible limit of the system. Accordingly, the optimal constructions for the low-dissipation three-terminal heat pump and heat transformer are determined within the frame of low-dissipation assumption, respectively. The optimal constructions in accord with previous research and engineering practices for various three-terminal devices are obtained, which confirms the compatibility between the low-dissipation model and endoreversible model and highlights the validity of the application of low-dissipation model for multi-terminal thermodynamic devices. The proposed models and the significant results obtained enrich the theoretical thermodynamic model of thermally driven heat pump systems and may provide some useful guidelines for the design and operation of realistic thermally driven heat pump systems. 相似文献
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V. E. Nakoryakov G. V. Nozdrenko P. A. Shchinnikov O. K. Grigoryeva 《Journal of Engineering Thermophysics》2010,19(2):53-61
The main provisions of the exergy method applied to analysis of heat and power plants are considered. Results of analyzing
power plants with state-of-the-art heat pump combined cycle heating systems are presented. 相似文献
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