| The Chinese government published policy of "Energy Conservation" in 2006, in this ten years, architecture designers tried hard to apply energy-saving measures on buildings, there has been many successful examples, one of them is using passive evaporative cooling measure on walls, this kind of walls we call it evaporative walls. At the same time, a problem appears, there is no available references and basic data which suits evaporative walls designing. There are many references for ordinary walls,if we just use such references to design evaporative walls, the designing cooling load will be too large, obviously, this is not reasonable. There are also complicated calculating methods which is able to do the math right, but it takes too much time and it’s very easy to make mistakes during the calculating. For the reasons given above, it’s necessary to find a new simplified calculation method for summer air-conditioning load of evaporative wall.In this paper, the concept and structure of evaporative walls are given. The procedure of how the evaporative wall functions is described. The problems about water source and pump power that evaporative wall takes are analyzed, and suggestions are provided. Heat and mass transfer process of evaporative wall are specifically analyzed. Formula of effective and comprehensive temperature is derived.based on FDR (frequency domain regression) method, a simplified calculation method for summer air-conditioning load of evaporative wall is introduced. Through an example, evaporative walls’effective and comprehensive temperature, heat transmission, cooling load, cooling load calculation temperature are specifically calculated, and the results of evaporative walls are compared with that of normal walls. Take Beijing as example, according to different orientation, thickness and structure of walls, a series results about evaporative walls’cooling load are calculated and analyzed. Cooling load calculating temperature of more than 30 major cities in China are calculated through Matlab programming based on the FDR method. The calculation provides conferences for engineering and the other small cities can get a fixed cooling load temperature from such conferences. There are four typical cities:Beijing, Shanghai, Xi’ an, Guangzhou, cooling load temperature and energy conservation and emission reduction of evaporative walls in this four city are calculated and analyzed. Combining with building climate type partition and dry-wet zoning, suitable regions of evaporative walls are determined. There are three main suitable regions of evaporative walls, energy conservation and emission reduction of three regions are evaluated and contrastive Analyzed. Also a building in xi’an was taken as an example, the water consumption of evaporative wall is estimated.The results show that using frequency-domain regression method to calculate the wall unsteady heat transfer, error is smaller, the calculation easier; For the evaporative wall, the influence of the temperature of evaporation to effective integrated must be considered, so as to get the correct reasonable effective comprehensive temperature; Evaporative wall can significantly reduce the wall heat gain and lower wall cooling load; east and west toward evaporative walls have better cooling effect, more suitable to become evaporative wall, the smaller the thickness of wall, the better of the evaporative walls’ cooling effect, more suitable for evaporative wall; the smaller the heat transfer coefficient of wall, the better of the evaporative walls’ cooling effect, more suitable for evaporative wall; there are three major suitable regions of evaporative walls:cold area of north China, hot summer and cold winter zone of central China, hot summer and warm winter area of south China; cold area of north China has best evaporative cooling effect, energy conservation and emission reductions for each day, hot summer and warm winter area of south China has best evaporative cooling effect, energy conservation and emission reductions for whole year. |
