严寒地区CO_2热泵热水器运行性能模拟研究

为减少严寒地区生活热水制备过程中的能源消耗,以CO_2热泵热水器为研究对象,建立了采用跨临界循环方式的CO_2热泵热水器的稳态仿真模型,模拟分析了CO_2热泵热水器在严寒条件下的运行性能。分析结果表明,在室外温度高于-13.9℃的条件下,CO_2热泵热水器能够正常运行,系统运行时COP高于2.67。文章的研究结果可为CO_2热泵热水器在严寒地区的推广提供参考。     

CO_2热泵热水器气体冷却器的选型与计算

在之前的研究中,根据设计工况对1台CO_2热泵热水器的水箱、压缩机进行了选型和设计计算。在上述基础上,对其气体冷却器进行选型与计算,设计出与系统匹配的气体冷却器。     

CO_2热泵热水器压缩机的选型与计算

分析CO2作为制冷剂的优良特性及其跨临界循环的特点,在给定工况下,对1台CO2热泵热水器的水箱、压缩机进行选型和设计计算,并提出提高CO2热泵热水器效率的建议。     

水源CO2热泵的全工况性能与匹配性分析

通过对60kW水源CO_2热泵的实验测试,在获得的911组实验数据的基础上,建立了用于反映热泵系统性能和循环参数随运行工况变化趋势的BP神经网络拟合模型,综合分析了系统在供水温度为55~100℃、回水温度为10~50℃、热源温度为5~50℃和电子膨胀阀开度为50~400步的全工况范围内的性能,从而为该类型热泵系统性能的预测和系统设计提供了数据参考。在对四种工况下,即15/55/15℃、15/90/15℃、15/90/30℃和30/90/30℃时系统运行参数的比较分析的基础上,定性评价了系统在全工况范围内的匹配性。     

热泵干燥系统运行特性的有效能研究

热泵干燥能源消耗少，环境污染小，干燥品质高，适用范围广，是一种性能优良的种子干燥机械。从热力学第一、第二定律两方面分析了热泵干燥系统的节能优势所在，得出采用辅助冷凝器是闭式热泵干燥系统的理想方式；而且热泵干燥系统存在一个最佳的蒸发温度，可使系统除湿率和效率最大。     

利用准二级循环提高跨临界CO2热泵热水器性能

提出了一种全新的应用于热泵热水器的准二级跨临界CO2热泵循环.经分析此循环可以有效降低压缩机的排气温度,提高热泵热水器的制热效率.这种热泵热水器尤其适用于寒冷地区.     

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。     

节能环保型CO_2热泵热水系统在浴室中的应用

考虑对某建筑楼浴室设计以CO_2作为媒介的新型热水系统去取代传统锅炉设备进行热水供应。采取了大温差小流量的运行方式,使得在稳定产热水的同时,既能节能环保,又能节约经济。从系统设计、性能优化、经济性的角度研究分析此系统的可行性,并对主要设备进行选型。最后将CO_2热泵设备跟传统燃油、燃气锅炉以及电锅炉设备进行对比并分析各项指标的优劣。     

水循环式热泵干燥装置的分析

热泵干燥装置具有节约能源、环境友好、可低温干燥等特点。水循环式热泵干燥装置是指热泵和干燥部分通过水循环耦合而成的热泵干燥装置,与热泵和干燥部分直接耦合相比,具有不向环境排放热量、机组调控性好、对干燥过程的匹配性好、成本低等优势,是一种较适宜于中小型热泵干燥装置的结构型式。     

直膨式跨临界CO2热泵地板辐射采暖的可行性分析

文中介绍了直膨式跨临界CO2热泵的工作原理,通过分析CO2制冷剂的换热特性、对比不同工况下CO2与传统工质热泵的性能来验证直膨式跨临界CO2热泵用于地板辐射采暖的可行性,并对不同负荷下的供热调节方式进行了计算分析。结果表明：直膨式跨临界CO2热泵地板辐射采暖在系统COPh、运行稳定性、经济性等方面都优于传统工质热泵,并且适宜用于室外温度较低的地区冬季采暖。     

用于污泥干燥的热泵试验研究

叙述了城市污泥干燥处理的必要性,对采用热泵形式进行干燥进行了理论分析,并对理论分析进行了实验验证。     

Performance assessment of contact heat pump drying

A comparative analysis is presented of a novel plate‐type isothermal heat pump dryer and a conventional adiabatic heat pump dryer. The energy performance and drying capacity of each dryer type is investigated subject to operational constraints on the maximum acceptable relative humidity and temperature of air passing over the product. The analysis demonstrates that for applicable products, a significant opportunity exists for improving the energy efficiency of heat pump drying, by a factor of 2–3 times compared with current adiabatic heat pump dryers. The moisture extraction rate is also increased in the contact heat pump dryer, by a similar factor. However, these improvements are shown to be sensitive both to the impact of product thickness on heat transfer and to the relative humidity constraint. Copyright © 2010 John Wiley & Sons, Ltd.     

Exergetic evaluation of drying of laurel leaves in a vertical ground-source heat pump drying cabinet

This paper is concerned with the exergy analysis of the single layer drying process of laurel leaves in a ground-source heat pump drying cabinet, which was designed and constructed in the Solar Energy Institute, Ege University, Izmir, Turkey. The effects of drying air temperature on exergy losses, exergy efficiencies and exergetic improvement potential of the drying process are investigated. The results have indicated that exergy efficiencies of the dryer increase with rising the drying air temperature. Moreover, the laurel leaves are sufficiently dried at the temperatures ranging from 40 to 50°C with relative humidities varying from 16 to 19% and a drying air velocity of 0.5 m s⁻¹ during the drying period of 9 h. The exergy efficiency values are obtained to range from 81.35 to 87.48% based on the inflow, outflow and loss of exergy, and 9.11 to 15.48% based on the product/fuel basis between the same drying air temperatures with a drying air mass flow rate of 0.12 kg s⁻¹. Copyright © 2006 John Wiley & Sons, Ltd.     

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.     

回热器对跨临界CO_2水源热泵的影响判别式及实验研究

分析了回热器对跨临界CO2压缩循环效率等的影响,推导出回热器对系统的制热效率影响的判别式。在带回热器和不带回热器两种情况下完成了跨临界CO2水源热泵系统的实验。实验结果表明：带回热器的跨临界CO2水源热泵系统的制热效率和制冷效率略高于不带回热器时系统的效率;带回热器时热泵系统的制热效率比不带回热器系统的制热效率高约4%-8%。     

Energy analysis of hazelnut drying system‐assisted heat pump

In this experimental study, a proportional integral derivative (PID) controlled heat pump dryer was designed and manufactured. Heat pump dryer was tested drying of hazelnut and energy analyses were made. Drying air temperatures were changed as 50,45 and 40°C in the drying system. Drying air velocities were changed as 0.25 m s^?1 for 50°C, 0.32 m s^?1 for 45°C and 0.38 m s^?1 for 40°C. Heating coefficient of performance of whole system (COP_ws) of the heat pump dryer was calculated as 1.70 for 50°C, 1.58 for 45°C and 1.40 for 40°C drying air temperatures. Energy utilization ratio changed between 24 and 65% for 50°C, 17 and 63% for 45°C and 14 and 43% for 40°C drying air temperatures in the heat pump dryer. Copyright © 2008 John Wiley & Sons, Ltd.     

Thermal performance of a solar-assisted heat pump drying system with thermal energy storage tank and heat recovery unit

Thermal performance parameters for a solar-assisted heat pump (SAHP) drying system with underground thermal energy storage (TES) tank and heat recovery unit (HRU) are investigated in this study. The SAHP drying system is made up of a drying unit, a heat pump, flat plate solar collectors, an underground TES tank, and HRU. An analytical model is developed to obtain the performance parameters of the drying system by using the solution of heat transfer problem around the TES tank and energy expressions for other components of the drying system. These parameters are coefficient of performances for the heat pump (COP) and system (COPs), specific moisture evaporation rate (SMER), temperature of water in the TES tank, and energy fractions for energy charging and extraction from the system. A MATLAB program has been prepared using the expressions for the drying system. The obtained results for COP, COPs, and SMER are 5.55, 5.28, and 9.25, respectively, by using wheat mass flow rate of 100 kg h⁻¹, Carnot efficiency of 40%, collector area of 100 m², and TES tank volume of 300 m³ when the system attains periodic operation duration in fifth year onwards for 10 years of operation. Annual energy saving is 21.4% in comparison with the same system without using HRU for the same input data.