Study On The Airflow & Temperature Field Characteristics In The Room With Wall Air Conditioner And On The Human Thermal Comfort

Air-conditioners are becoming more and more popular with the development of economy, and the so-caused air-conditioner syndrome and energy problems caught more and more attention, which could affect people' health directly. Therefore, it is very important to study the distribution characteristics of airflow and temperature field under different air supplies condition in a room with wall air-conditioner and discuss the relationships between the indoor airflow and thermal comfort, thus bring forward the reasonable usage of wall air-conditioner to improve indoor air quality and reduce the energy consumption. To search for the experimental research method of human thermal comfort and establish the evaluation model of human thermal comfort in different thermal environments will also provide important theoretic instruction for the further practical control method and strategy of indoor thermal comfort, and that will facilitate the development of room air-conditioner.In this paper, firstly the distribution characteristics of airflow and temperature field in an actual room with wall air-conditioner were studied under different air supply parameters, such as the airflow angle and speed when the air-conditioner was running for refrigeration. The distributions of temperature were detected by a self-made temperature acquisition system.The experiment results show that the temperature reducing rate is affected greatly by the angle of air deflector and air supply speed. When the angle was 45°, the room temperature reduced very fast, the temperature difference between contiguous layers was the least and human thermal feel was quite fine, and the degree of indoor thermal comfort was quite high. The upper part of the room is hot while the lower cool, which shows a stratification phenomenon. The effect of air supply parameters on the wall temperature is quite little, which could be ignored.Base on the experiment situation, numerical simulation through FLUENT software was carried out to study the distribution characteristics of airflow and temperature field under different air supply conditions when the wall air-conditioner refrigeration. Compared with the foregoing experimental results under the similar conditions, the computational simulation results can reflect the distribution characteristics of airflow field and temperature field correctly, which shows that the model is rational and feasible. The thermal comfort degree and energy consumption under different air supplies of the room with wall air-conditioner could be evaluated more reasonably with the modified air diffusion performance index (ADPI) and energy utilization coefficient (EUC). The smaller the angle of the air reflector is, the larger is ADPI and the more comfortable is the room. The bigger the angle of the air reflector is, the larger is EUC and the higher is the economical efficiency.The same numerical simulation method was also carried out to study the distribution characteristics of airflow and temperature field under different air supplies when the wall air-conditioner was running for heating. It was found that the temperature increasing rate is affected greatly by the angle and wind speed. When the air reflector angle is 105°, the temperature increases fastest and the temperature difference between layers is the least, meanwhile the human thermal feel is quite fine and the thermal comfort degree is high. Furthermore the larger the air refector angle is, the less is the temperature difference between the return air and the room average air temperature. The larger is the angle of air reflector, the larger ADPI and EUC are, the more comfort and the less energy consumption are.According to thermal comfort theory, a computational program which could quantitatively analyse the effects of thermal environmental factors on predicted mean vote (PMV) index was compiled by using Matlab technique. Base on subjective and objective questionnaires about human thermal comfort, the neural network (NN) model of thermal comfort was established and validated by experimental results. It was found that the value of PMV increased with the room temperature, relative humidity and average radiation temperature, the relationship between them is almost of direct proportion. The value of PMV reduced sharply as air speed increased. The NN prediction results are agreed well with the target value. The NN could be trained by using individual study sample to solve the thermal comfort problem that different persons in the same thermal environment have different feeling, which will be more useful for the development of individual air-conditioner.The airflow field and temperature field in the room with wall air-conditioner and the human thermal comfort degree were studied systematically, the research results will be very helpful for the correct use and improvement of air-conditioner.