地源热泵技术在中国温室设施中的应用探讨

当前在中国温室设施中应用和推广地源热泵技术尚存在诸多不利因素,大大限制了该项技术在设施农业领域中的发展。为探寻合理的解决途径,对地源热泵空调系统的关键技术和其在中国的发展概况进行了相关的阐述和分析,并以中国农业大学上庄实验站已经建成使用的地下水式温室地源热泵空调系统为实例,介绍该系统的组成、工作流程、性能参数和使用情况,探讨温室地源热泵空调系统在推广和使用中可能出现的投资较高,长时间运行性能不稳定等问题,分析其原因并提出相应的对策建议。     

Exploration of Feasibility of Applying on Ground-Source Heat Pump in Western Region of China

The brief introduction to properly applying HVAC to the sustainable west development of China is made in this article. The advantage of GSHP, a branch of HAVC, is also presented briefly here. The emphasis is put on the fact that this system is a green one which sustainable and practicable characters. At the same time, the comparison between the key technique of GSHP and the geological condition that the system should adjust to is made, which reveals the key point of applying GSHP. According to environment condition, three types of areas are divided in the western regions of China. The feasibility of applying GSHP in each area is explained respectively and the related scheme of applying the system is also summed up.     

农产品空气能热泵烘房温度场的数值模拟与验证

农产品热泵烘房温度场均匀性是影响农产品干燥品质的重要因素。本文选用5HGR-35型农产品热泵烘房,通过交互式CAD/CAM系统(UG)软件建立热泵烘房3D模型,运用理论分析与计算流体动力学(Computational fluid dynamics,CFD)模拟相结合的方法,研究其内部温度场分布情况,对现有结构烘房的温度场建模模拟,分析模拟结果并对现有结构进行优化。通过模拟得出结论:送风速度越大,烘房内热空气更新越快,换热效果越好。综合温度场分布以及农产品烘干要求,烘房内合理的送风速度为11 m/s左右;在11 m/s风速下,烘房空载时在15 min左右达到设定温度(65℃);小推车设计高度加大300~310 mm烘房内部温度场更均匀;烘房顶部均匀加入3块长×宽×高=2900 mm×20 mm×300 mm的挡板,可以使烘房内部温度场更均匀;小推车与烘房之间及相互之间保持30 mm左右间隙摆放更有利于烘房内部温度场的分布;验证试验中,模拟温度与实测温度吻合性良好。上述结论对烘房的进一步优化设计具有一定的指导意义。     

Analysis of the Ground Adjustment Ability of the Ground Source Heat Pump Systems in Winter

Based on an actual ground source heat pump system in hot summer and cold winter area, the system operation parameters were tested for 6 years under the state of using cooling tower for cooling in summer but the ground heat exchanger and fire pool for heating in winter. A three dimensional (3D) tube group model was established, and the thermal balance analysis and calculation of the ground temperature distribution around the ground heat exchanger were conducted by the numerical calculation. According to the comparison between the test data and the theoretical results, the influencing factors of the ground adjustment ability were obtained.     

Experimental Analysis on Characteristics of Energy Storage for Defrosting of Air Source Heat Pump with Phase Change Energy Storage

The performances of energy storage modes are experimentally analyzed in the artificial environment in order to study the effect of energy storage modes for defrosting of air source heat pump with phase change energy storage. Results indicate that suction and discharge pressures are stable at 038 MPa and 165 MPa under the series energy storage mode, and suction and discharge temperatures are 6.9℃ and 75.0℃ respectively. However, the suction and discharge pressures are as low as 012 MPa and 116 MPa in parallel and single energy storage modes individually, and the discharge temperature is up to 1225℃. In addition, in series energy storage mode, the phase change material can completely change from solid to liquid in energy storage process. The temperature difference is about 18.0℃ for indoor coil, and the input power to compressor is 825W. Therefore, the system pressures and temperatures are most stable in the series energy storage mode and the time for energy storage is short, which can meet the need of defrosting energy.     

Design and Construction of an Air Conditioning System Employing a Ground Source Heat Pump Combined with a Radiant Floor

The air conditioning system using a ground source heat pump(GSHP) combined with a radiant floor integrates the advantages of both types,giving such a system large potential for popularization.After experimenting with one house's hybrid system,the design processes and construction methods for such a system can be summarized.In the experiment,different terminal devices were used to adopt varying winter and summer climatic conditions.It is suggested that the constructors should make good use of resources and waste water during the construction phase.The experimental results show that this hybrid system runs steadily and it supports a better temperature field to meet the requirement for the human comfort.Finally,a hybrid system managment strategy is suggested.     

Energy Efficiency of Water Transportation System for Surface Water Source Heat Pump

The forms of water transportation, arrangement and operation of pumps contribute to the water transportation energy consumption, which influences the energy-saving effect of surface water source heat pump. The relation between the pumping height and energy consumption of pumps is found by analyzing the model of pump energy consumption. The concept and calculation of critical pumping height is presented considering the limited rate of system energy efficiency. Based on the principle that the pump power changes with water flow rate, the determination of pumps arrangement of one or two stage pumps is described with a concrete example. The influence of water flow rate on heat pumps and water pumps is analyzed, and the energy efficiency of constant and variable water volume are compared. The operation way of this example is concluded for the optimal system energy efficiency. It is found that there is a critical pumping height for the energy-saving effect of surface water source heat pump compared with the traditional system. Moreover, the operation strategies should be determined by the system optimal model since the energy consumptions proportions of heat pumps and water pumps are variable.     

Study on Simulation Method of Heating and Air - conditioning Energy Consumption of Residential Buildings

The heating and air conditioning energy consumption of residential buildings is influenced by the behavior of indoor living personnel.On the basis of research and analysis,two kinds of calculation modes reflecting the behavior of indoor living personnel are estimated.Under two kinds of different calculation modes,by using the building thermal environment simulation Toolkit DeST to simulate the energy consumption calculation for certain residential building in Shanghai,and the simulation results are compared with the research results.The influence of calculation mode on heating and air conditioning energy consumption of residential buildings in Shanghai is analyzed in this paper.In order to obtain the right simulation calculation method correctly reflecting the energy consumption of residential buildings.This method can be used for analysis and evaluation of heating and air conditioning energy consumption of residential buildings in Shanghai,and it can serve as instruction for right energy design of residence building.     

Performonce of Fouling Fluidized-Removing and Heat Transfer Enhancement on Sewage Side of Sewage-Source Heat Pump System

High thermal resistance resulted by fouling in heat exchanger restricts the application of sewage source heat pump (SSHP) system. The fouling forming mechanism was applied with solid-liquid fluidized bed technique for fouling prevention and removing of SSHP system. Shearing stress model of solid-liquid fluidized bed heat-exchanger is analyzed, and collision stress model is modified. Preventing and removing fouling mechanisms of solid-liquid fluidized bed technique by shearing stress and collision stress was explained. An experimental study on how to solve the fouling problem (such as fouling prevention and removing, heat transfer enhancement, etc) is discussed. The results of theory and experiment show that solid-liquid fluidized bed technique can be used not only to increase convection coefficient, but also to restrict fouling growing, it can effectively solve the fouling problem in SSHP system.     

水源热泵在温室加温中的应用研究

采用多层覆盖、减小直接加热空间的温室节能设计措施,设计建造了试验温室,在水源热泵热风加温条件下,对试验温室的温度、空气相对湿度、水源热泵的实际制热系数进行了测定,对试验温室采用水源热泵加温的节能效果进行了评价,结果表明：夜间水源热泵加温条件下,温室东西方向的水平温度分布均匀,南北相距12m的水平方向上存在着0.9℃的温差,中部距地面2.2m的垂直空间上平均存在1℃的温差,24:00—08:00,空气相对湿度低于80%;试验用水源热泵实际热系数为3.31。与燃煤锅炉热水加温的玻璃温室相比,试验温室采用水源热泵加温相对节能46.5%,直接加温成本较燃煤锅炉加温高82.2%,经计算,当试验温室与对照玻璃温室面积相等时,采用水源热泵加温可相对节能69.1%,直接加温成本仅较燃煤锅炉加温的玻璃温室高5.8%。     

Green Thought on the Energy Saving of Air Conditioning

This paper points out the problems in air conditioning and the urgent need in energy saving. By observations and analyses, it shows that the idea of making use of natural resources to improve the indoor air may date back to ancient times. This paper also examines the feasibility of taking advantage of dry or wet bulb temperature, solar energy, underground rock etc. to regulate the room temperature. Finally, it concludes that the above mentioned old idea has such characteristics as energy saving, low cost and less pollution. Therefore, it is a good green plan in energy saving air conditioning.     

热泵技术在温室中的应用

为了探究热泵技术在农业领域可持续发展的应用前景,通过对热泵的发展概况、工作原理以及在各种温室上的应用展开分析探讨。综述了国内近20年的热泵在温室上的应用,研究表明：热泵在温室的应用上存在着一定的地域局限性和环境局限性,而复合型热泵可以通过相互间的取长补短打破这一局限性。因此今后需要将复合型热泵作为重点研究对象,促使热泵在温室上应用更为广泛。热泵系统作为一种节能、高效、环保的新型节能技术,受到大众的青睐,在农业领域的可持续发展有较好的应用前景。     

黑皮冬瓜分段式变温热泵干燥工艺研究

为提升黑皮冬瓜干燥品质及降低干燥能耗,对黑皮冬瓜分段式变温热泵干燥工艺进行了研究。通过研究湿度对冬瓜干燥过程、瓜干品质及干燥能耗的影响,确定了最适相对湿度为40%和50%。根据最适湿度条件下干燥前期温度的波动情况设计了4种分段式变温干燥工艺,采用综合加权评分法对4种工艺进行比较,得到了最适分段式变温热泵干燥工艺为:温度50℃(5 h)-60℃(至结束),相对湿度50%,循环风速1.5 m/s,瓜片厚度6 mm。将热泵干燥方式与传统的电热干燥方式进行比较,发现热泵干制的瓜干品质显著优于电热干制的瓜干(P0.05),热泵恒温干燥较电热恒温干燥节能38.93%,热泵变温干燥可在进一步提升瓜干品质的同时较热泵恒温干燥节能11.25%。     

Improvement of Method in BIN Building Energy Consumption Calculation

The proportion of radiation load through glass windows in building energy analysis is comparatively great;it is regarded as linear relation with temperature in BIN method,which is extremely a rough method.It is not only because the relation between such radiation load and temperature is far from linear relationship,but also there is lack of objective standard for the selection of corresponding representative temperature to the load.To solve this problem,calculating the maximum factor D_(J max) firstly,then get the hourly corresponding relation of load and temperature by multiplying the hourly cool load coefficient.The practical relation of load and temperature could be obtained by counting up the average load to each temperature at each direction;the load calculation method is still simple using a series of statistic data.A comparison has been made between this method and the former one.As it is the real reflection of relation between the temperature and load,the precision of load calculation is enhanced.The process using this method to calculate load for south facing window in Chengdu is given in this paper.     

Experimental Comparison of Low-temperature Hydraulic Heating Floor and Heat Pump Air-conditioning

In this paper the low-temperature hydraulic floor heating system of a residence in Chongqing was tested. The influence of this system and the heat pump air conditioning system on indoor thermal comfort and operation cost was analyzed and compared. The effect of heat dissipation by radiation and convention of the floor was analyzed. It shows the feasibility and advantage of floor heating system in Yangtse River Region.     

Effects of Operation Mode of Air Conditioning on Energy Consumption of Heating and Air Conditioning in Residential Buildings

By using the building thermal environment simulation Toolkit DeST to simulation calculation of a residential building in Shanghai,the quantitative relationship between the factors of operation mode of air conditioning affecting the energy consumption of heating and air conditioning in residential buildings has been obtained in this paper,moreover,it has come to a conclusion that the tolerable temperature is superior to control temperature of air conditioning in respect of sensitivity and the living mode of indoor personnel has certain effect on the cold energy consumption.     

Comparative Analysis of Heat Exchange Performance ofEnergy Piles and Borehole Heat Exchangers in GSHP System

Due to their enhanced cost-effectiveness and efficiency over traditional borehole exchangers, energy piles are increasingly used in Ground Sourced Heat Pump (GSHP) projects. In this paper, the structural characteristics of these two types of heat exchangers and their heat transfer mechanism were discussed firstly. The thermal response tests (TRT) were performed on two testing energy piles in one GSHP project in Nanjing, China. The TRT results were then used to verify the numerical simulations, which suggests that the heat exchange performance of energy piles is superior to that of the traditional borehole exchangers. Meanwhile, the numerical simulation method used in this paper was considered applicable to the optimization design of ground heat exchangers in GSHP system.     

Mathematical Model and Operation Analysis of Semi-submerged Rotary Orifice Sewage Source Heat Pump Intake Machine

To solve the flow instability and adjustment difficulty of filtering dirt-removing device in the sewage source heat pump system, which affect the efficiency of heat exchanger, semi-flooded rotary orifice sewage auto-strainer was generated. According to establishing the mathematical model, the effect is analysed of pollutant concentration and liquid level height of sewage and rotation period of orifice plate to filtered flow rate, filtered load and filtering surface block coefficient. The result shows that: in the certain condition of sewage liquid level height and orifice plate rotation period, the increase of sewage will decrease the filtered flow rate of orifice plate, and increase filtering surface block coefficient; The effect of pollutant concentration change in the sewage to orifice plate filtered flow rate could be adjusted by regulating the sewage liquid level height and orifice plate rotation period, and the moderating effect of orifice plate rotation period is better than that of sewage liquid level height.     

Effects of Heat Transfer Coefficient of External Window on Residential Buildings in Subtropical Areas

Using Designer's Simulation Toolkit DeST h developed by Tsinghua University, research was carried out on the energy consumption of a typical residential building in Ningbo, P. R. China, with a focus on the heat transfer coefficient of external windows facing every direction. Results show that variation of the heat transfer coefficient of external windows in all directions has a substantial effect on energy consumption for heating but little effect on energy consumption for cooling. It is difficult to decrease cooling energy consumption by decreasing the heat transfer coefficient of external windows in summer. The heat transfer coefficient of external windows facing south has a significant effect on building energy consumption, but the windows facing north have less effect, and those facing east and west have the least impact. Decreasing the heat transfer coefficient of external windows facing north and south from 4.7 to 3.2 produces the most favorable performance cost ratio for energy saving investments. Reasons for the decrease in the heat transfer coefficient of external windows leading to increased air conditioning energy consumption were discussed. The conclusions are useful for guiding energy efficient building design in other subtropical cities.