建筑供暖与制冷能量系统（火用）分析及应用研究

发布时间：2018-03-09 13:56

本文选题：建筑能量系统　切入点：采暖和制冷　出处：《湖南大学》2013年博士论文　论文类型：学位论文

【摘要】：能源是发展生产力和提高人类生活水平的基础，能源的短缺促使人们意识到节能的重要性，但是要回答何谓节能其实并不简单，只考虑能量平衡的热力学第一定律回答不了这一问题，从能量利用价值角度看，节能实质上是对常规能源中的可用能“火用”的节约与利用。本文基于热力学第二定律的火用分析方法，提出了从建筑能源的转换、输送到用户终端能量使用全过程，即从一次能源到围护结构建筑能量系统的火用分析理论模型，详细探讨了火用分析对环境状态选择的敏感性，主要研究内容和成果包括以下几方面：首先，以全国27个典型城市的气象数据为依据，研究静态和逐时变化的环境基准状态对空气处理过程火用分析结果的影响。结果表明，夏季气候高温湿热的地区，对空气冷却处理过程进行火用分析时，湿空气的化学火用不能忽略，静态和逐时变化的两种环境基准状态下火用分析结果误差不大，因此可用室外平均温度和湿度代替逐时变化的温度和湿度。对于有空调期的大部分城市来说，静态和逐时变化的两种环境基准状态下的化学火用误差较小，在计算湿空气火用值时，可用空调期室外平均湿度替代逐时变化的室外湿度。采暖期，对空气加热处理过程进行火用分析时，静态和逐时变化的两种环境基准状态下的火用分析结果误差较小，因此采暖期空气加热处理时可用室外平均温度代替逐时变化的温度作为环境基准温度。其次，以分体式热泵空调系统为例，以典型气象年逐时变化的室外温度和湿度作为环境基准状态，基于制冷状态下空调房间室内空气的化学火用，建立了从一次能源到围护结构分体式热泵系统能量流动的火用分析理论模型，并将其应用到工程实例中，结果表明，对于夏热冬冷地区，围护结构适度保温是必须的,但不应一味的增加保温层的厚度；在适度保温的前提下，应重点考虑提高热泵系统效率，这样建筑能量系统的能源利用效率才能达到最佳。一次能源阶段和热泵阶段的火用损耗约占系统总火用损耗的80%以上，因此改善这两个阶段是提高系统火用效率的关键。在此基础上，根据建筑供暖与制冷系统能量流动过程，包括围护结构、室内空气、末端设备、管网系统、冷热源和一次能源转换环节。建立系统各环节的火用分析理论模型及评价指标。应用火用分析理论模型，对某办公大楼不同方案的能量系统从围护结构到一次能源转换进行火用分析，计算各环节的火用流、火用损、火用损率和系统火用效率，根据火用分析计算结果，评价不同建筑能量系统的优劣。结果表明，系统中火用损最大的环节是一次能源转换，冷源方案一次能源阶段火用损率为64.8%~92.2%，热源方案一次能源阶段火用损率为64.6%~84.3%。另外，分析建筑能量系统时应考虑能量梯级利用的原则，在能量利用过程中,能级差越大,火用损失越大。本文提出了采用一次能源火用效率和能级平衡系数评价建筑冷热源和末端设备。以1KJ冷量和热量为例分析末端系统不同供回水温度火用效率和能级平衡系数，结果表明，采暖期末端设备尽量采用低温热水，且尽量减少供回水温差；空调期末端设备尽量提高供回水温度，且尽量增大供回水温差，这样系统火用效率和能级平衡系数才能达到最优。因此，在末端设备系统中，应尽量采用接近室温的冷热介质。最后，提出了火用分析结合建筑生命周期方法评价既有建筑改造后的节能效果，运用该方法对某建筑节能改造实例进行了分析，结果表明，对于建造年代久远的建筑，在进行围护结构节能改造时，，应当把改造后的节火用效果、节能效果和环境影响作为一个整体进行综合分析。
[Abstract]:Energy is the development of productive forces and foundation to improve the level of human life, the shortage of energy makes people realize the importance of saving energy, but to answer what is such is not simple, only consider the energy balance of the first law of thermodynamics can't answer this question, from the angle of energy utilization value, such is the essence of conventional energy in the available energy "and using energy saving". In this paper, based on the second law of thermodynamics exergy analysis method, proposed the transformation from the building energy, transportation to the user terminal energy used in the whole process, from an energy exergy building envelope energy system analysis model, discusses the exergy analysis of sensitivity to the environment state of choice. The main research contents and achievements include the following aspects:
First of all, to the national meteorological data of 27 typical city based on the environmental impact of reference state to study static and hourly variation of the air handling process of exergy analysis. The results show that the climate in hot humid summer, exergy analysis of air cooling process, the chemical exergy of moist air can not be ignored, the analysis results the error is not two static and hourly changing state environmental standards under the exergy, so it can be the average outdoor temperature and humidity instead of hourly variation of temperature and humidity. For most of the city air conditioning period, the chemical exergy error of two static and hourly changing state environmental benchmark under the small, in the calculation of the wet air the exergy value, outdoor humidity available outdoor air conditioning period average humidity instead of hourly variation. The heating period, exergy analysis of air heating process, static and hourly variation The error of exergy analysis under two environmental reference states is small, so the outdoor mean temperature instead of the hourly change temperature can be used as the reference temperature in heating period.
Secondly, the split type heat pump air conditioning system as an example, the typical meteorological year changed hourly outdoor temperature and humidity environment as the reference state, under the condition of chemical exergy refrigeration air conditioning room indoor air based on established from an energy to envelope exergy flow analysis model can split heat pump system, and it is applied to the engineering example, the results show that the hot summer and cold winter, moderate heat retaining structure is necessary, but should not blindly increase the thickness of the insulation layer; in the premise of moderate heat preservation, the focus should be to improve the efficiency of heat pump system, the energy efficiency in order to achieve the best way of building energy system. A stage and stage of energy heat pump exergy loss accounted for more than 80% of the total exergy loss, thus improving the two stage is the key to improve the exergy efficiency of the system.
On this basis, according to the building heating and cooling system in the process of energy flow, including building, indoor air, terminal equipment, network system, cold and heat sources and energy conversion. The exergy of each part of the system analysis theory to establish model and evaluation index. The application of exergy analysis model, energy system of an office building in different schemes the primary energy from retaining structural transfer exergy analysis, exergy calculation of flow, exergy and exergy loss and exergy efficiency of system, according to the calculation results of exergy evaluation, different building energy system. The results show that the largest part of the system exergy loss is an energy conversion, cold source schemes a stage of energy exergy loss rate is 64.8%~92.2%, an energy source stage of exergy loss rate was 64.6%~84.3%.
In addition, the analysis of building energy system should consider the principle of cascade utilization of energy, the energy utilization process, energy difference is bigger, the exergy loss is greater. This paper presents the use of primary energy and exergy efficiency of energy balance coefficient evaluation of building heating and cooling system and terminal equipment. The 1KJ cold and heat for the analysis of different supply and return water temperature the exergy efficiency and energy balance coefficient, end system results show that the heating terminal equipment as far as possible the use of low temperature hot water, and try to reduce the supply and return water temperature; air conditioning period end equipment to improve the supply and return water temperature, and to increase the supply and return water temperature, so the exergy efficiency of the system and the energy balance coefficient to achieve optimal. Therefore, in terminal equipment system in the cold and hot medium should be used close to room temperature.
Finally, put forward the energy saving effect of exergy analysis and evaluation method of building life cycle combined with the existing building after the transformation, this method is used in the example of a transformation of building energy saving is analyzed, results show that, for the construction of the age of the building, the energy saving renovation of retaining structure, should be transformed section exergy effect, energy saving and the environmental impact as a whole comprehensive analysis.

【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU111

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