| According to the requirements of the scientific outlook on development, adjusting the energy structure of our country, promoting the energy diversification, innovating technical and developing new energy has become an urgent task. Compare with other new energy, dry air is clean, no pollution, does not destroy the ozone layer, the resources are widely distributed, suitable for on-site development and utilization. It also can be use continuously, having high density, high efficiency, can be directly used without energy storage device. Especially dry air can replace conventional energy as the power source of the cooling air conditioning system, it is a way of sustainable utilization of new energy.Evaporative cooling air conditioning technology is the use of liquid water in dry air to reduce temperature. In other words, the water and dry air through heat exchange to get low temperature cold wind and cold water. When water vapor partial pressure of dry air in the unsaturated state, it has the ability of isothermal, as long as water appear, dry air will be converted into heat energy. For dry areas, the outdoor dry air is a new type of inexhaustible and renewable energy. Evaporative cooling technology with energy saving, environmental protection, high efficiency, good air quality, and many other advantages, is a real sense of sustainable development of refrigeration technology. At present in our country in the western region has received a degree of promotion. Evaporative cooling air conditioning technology according to the cooling process can be divided into two types: direct evaporative cooling and indirect evaporative cooling. In direct evaporative cooling(DEC), air which to be processed in the spray chamber contact with water spray, dry air in the water evaporative cooling for low temperature wet air, the treatment process is enthalpy of cooling process, such as dry air temperature is to reduce the humidity increase at the same time. So the direct evaporative cooling is suitable use for the hot, dry regions, or a occasion requair cooling and humidifying. In indirect evaporative cooling(IEC), air(primary air) which to be processed in the pipe and the air(secondary air) which be used for evaporative cooling outside the pipe. Primary air separated by pipe through the pipeline for table cold without humidification, so it can be more widely used. In promoting energy conservation and environmental protection of today's society, evaporative cooling air conditioning technology will constantly promoted and applicated to most areas in China.If you just use direct evaporative cooling or indirect evaporative cooling, the temperature drop range is limited, difficult to achieve a sharp cooling, its application will usually restricted by regional or using site. In order to achieve substantial cooling, the domain experts put forward the combination of direct and indirect forms of multi-stage evaporative cooling unit. Efficient unit can treat the temperature of primary air to lower than outdoor air wet bulb temperature, or even close to the air dew point temperature. But as a result of these units with the increase of level, the equipment structure become large and complex, it has high energy consumption, high operation difficulty, the applicable scope is small, not suitable for use in residential buildings and some commercial buildings. Therefore, improve multi-stage evaporative cooler in thermal efficiency, increase the scope of application is the urgent need to study of cooling technology.Based on the evaporative cooling air conditioning of the strengths and weaknesses, this topic proposed a completely innovative triple tube type indirect evaporative cooling air conditioning unit. The purpose of the study is: implementation unit modular design, make the units at the beginning of less investment, easy to control, and high cooling efficiency. And the processor are compared with existing multi-stage evaporative air cooling, dry air energy indirect evaporative cooling and indirect evaporative air cooling chillers. It is concluded that the advantages and disadvantages of this topic designed units and using range.This article first briefly analyzes the domestic and foreign multi-stage research situation of tubular indirect evaporative cooler, the purpose of this new unit study, significance, methods, and is currently in the field still exist some shortcomings and problems. And compare with the three levels traditional tube type indirect evaporative cooler than on the basis of the relative diagram to design new unit structure, analyzes the advantages and disadvantages of the new unit. The unit on the structure of the biggest characteristics is the second and third level of the secondary air are derived from the higher level of primary air and secondary air temperature is so low, so to improve the overall efficiency of the unit; Of course, this leads to a large air volume, making large unit.After detailed analysis of the heat exchange pipes inside and outside the heat and mass transfer process and the specific process of air, spray water flow, determined the different heat and mass transfer in the process of heat transfer coefficient. On the basis established mathematical model of tube type indirect evaporative air cooling. Heat and mass transfer characteristics of cooler simulation study of heat and mass transfer was analyzed by using the Fluent software to calculate and process, the heat exchanger under different physical parameters and fluid parameters within the evaporative cooling process in the three dimensional numerical simulation. The main parameters are: the primary and secondary air and spray water temperature, pressure and velocity in the channel, and used the image of the chart says out of the channel and the distribution of the different parameters change over time.Then calculate the influence of multistage tubular indirect evaporative cooler heat and qualitative theory of many factors. Mainly studied the following effects on the efficiency of the cooling: air wet bulb at a time, secondary air wet bulb temperature, one, two air velocity, secondary/an air volume ratio, the size of the spray water and etc.Finally, according to the simulation results, determine the air volume back to unit, per level distribut volume(enter this air volume size and indirect pipeline at the corresponding level for direct evaporative cooling of the secondary air volume size) at the corresponding levels, each level of the import and export air dry wet bulb temperature, spray water amount and its temperature, energy consumption and cooling efficiency of the unit. On the basis of established a three-level detailed structure of tube type indirect evaporative cooling unit. Equipment distribution within the dimensions including shell, filter, blower, spray water machine, water pump, spray water pipe, heat exchange tube, air valve, air duct equipment such as the specific type and material, and comparing with the conventional unit. |
PDF Full Text Request