Energy And Exergy Analysis Of Air-conditioning Room In Summer

The shortage of energy resources tends to be more serious and the pressure of environmental protection is heavier. Among that, energy consumption of air conditioning system takes up a great proportion, so it is an important mission for us to study and analyse the energy c onsumption air conditioning system. At present, there are two methods in study of energy system.The first one is the analys is method of conservation of energy. Although simple, it only judges various types of energy by quantity rather than quality, it is difficult for us to describe various irreversible energy losses; The second one is the analysis method of exergy, which can judges various types of energy by quality and quantity. This method reflects the nature of the energy, energy transfer and energy loss and is more scientif ic and more comprehensive. The paper mainly adopts the theory of exergy analys is to analyse and evaluate the energy consumption of air-conditioning system in summer, and discusss the thermal comfort of people in the air-conditioning room.Firstly, this paper studies the selection of referencing point of environment for exergy analys is and draws a conclusion that no matter which referencing environment to choose to be the reference point, there are no obviously difference to identify a better one. In fact, according to the specific object of study and relevant requirements, an accurate reference point can be elect out. Now, to investigate the effect of outdoor environment on air-conditioning room in summer of Shanghai, this paper analyses the refrigeration units, conveying and terminal equipments of the air-conditioning system by the method of exergy analysis. Results indicate that with the outdoor temperature increasing, the exergy of air-conditioning room varys as a parabla and increases constantly, meanwhile, the conveying exergy also goes up, however, the COP( coefficient of performance) of chiller plants reduce. Under the condition of the same outdoor temperature, the larger supply-air temperature difference is, the smaller adjustable exergy will be.In addition, to investigate the stratified air-conditioning system of a exhibition hall, cooling load and exergy load at different stratified heights( Z=4.5m,6.5m,8.5m,10.5m) are calculated and analysed: the proportion of energy saving at the stratified height of 4.5m comes to 29.3%,and the proportion of energy saving at the stratified height of 10.5m comes to13.3%. From the exergy analys is, the minimum work of applying to remove waste heat and humidity is extremely small, moreover, the latent heat exergy of indoor air, the sensible heat and latent heat of fresh-air are independence of the stratified heights.An model of exergy balance system was established for human body, and under the premise of the basal metabolic rate, the input exergy, output exergy, storage exergy and exergy consumption rate of different age people groups in one air-conditoning room are compared and analysed; Besides, the optimum thermal comfort of different age people groups in one air-conditoning room in summer by exergy consumption rate of human body and the index of PMV( Predicted Mean Vote). Results demonstrate, for the same age people group, the lower room temperature is, the larger exergy consumption rate will be, the corresponding temperature of the minimum value of the exergy consumption rate are exactly right in the thermal comfort threshold value of PMV; And the corresponding room temperature of the optimum thermal comfort of different age people groups are various, so the index PMV can not exactly reflect the thermal comfort feeling of the old group up 60 and the young group between 11 and 12; However, HEC(Human Body Exergy Consumption Rate)can not only be an index to estimate the human body thermal comfort,but also respond the thermal comfort feeling of different age groups.