Experimental Study On Evaporation Cooling And Energy Saving Of Porous Phenolic-concrete Composite Test Block Of Roof

Today's air conditioning technology brings people a comfortable environment on the one hand and consumes a lot of energy on the other hand,causing a serious negative impact on the environment.How to reduce the building energy consumption has become one of the important contents of the current energy conservation work.Passive cooling technology refers to the technology that does not consume conventional energy or USES natural cooling sources for cooling.Evaporative cooling is a technology that USES the evaporation of liquid water to take away a lot of heat to achieve cooling.Placing porous material on the outside of the building makes use of its characteristics of water absorption,water retention and evaporation to cool the building,which can not only improve the indoor thermal environment in summer and play an energy-saving effect of cooling,but also make full use of natural rain water or condensate of air conditioning,etc.,which is an economical,effective and convenient passive evaporative cooling technology.However,existing research and porous materials used for evaporative cooling(such as wet sand,aerated concrete,decorative tiles,etc.)have poor water absorption and water retention,which will be quickly dried in the sun in practical applications,and it is difficult to maintain long-term evaporative cooling effect.Therefore,it is of great practical significance to develop porous evaporative materials or components with good water absorption and water retention.Porous phenolic materials are widely used in the field of water absorption and preservation of vegetation and flowers due to their advantages of strong water absorption,good water retention,low cost and light weight.However,porous phenolics are vulnerable to aging and brittle failure due to direct exposure to outdoor climatic factors,and are difficult to be used as porous materials in passive evaporative cooling technology alone.In order to retain the advantages of porous phenolic water imbibition is strong and good water retention,overcome the disadvantage of its aging or fragile failure,this paper puts forward the porous phenolic with concrete cladding forming composite block with exterior opening,made and tested different compressive properties of the composite block,water absorption and evaporation properties,and through the optimization of composite block,tested it for roofing passive evaporative cooling and energy saving effect,mainly done the following several aspects work:1.Nine kinds of porous phenolic-concrete composite test blocks were designed and manufactured by orthogonal experimental design method,considering the influence of external pore diameter,porosity and concrete aggregate ratio.The test results show that :(1)the compressive strength of specimens increases with the increase of the ratio of coarse aggregate to cement;The test block with the ratio of coarse aggregate to cement of 2.8:1 has better compression resistance than other test blocks.(2)adding cross concrete rib to the test block can effectively improve the compressive performance of the test block,and there is an obvious inflection point in the curve of compressive performance.2.Different test pieces were immersed in water,and the maximum water absorption rate of different test pieces was measured by weighing method.The water evaporation performance of different test blocks under the action of outdoor climate was tested by placing the test pieces under the sun without blocking.The test results show that(1)the hydroscopicity of the composite test block mainly depends on the internal phenolic material and has little relation with the porosity,pore size and ash collection ratio.(2)the porous phenolic-hydrocoagulation composite test block with external opening aperture of 15 mm and porosity of 4.5% has a better water evaporation performance.3.Based on the composite specimen compressive properties,water absorption and evaporation performance of comprehensive consideration,choose the better comprehensive properties of porous concrete composite phenolic block as roofing passive evaporative cooling energy compaction test piece,it laid to the test houses on the container,in a typical summer climate condition,the contrast test on the porous concrete composite phenolic block passive evaporation roof cooling and energy saving effect.The test results show that :(1)compared with the container without any treatment on the roof,after the porous phenolic-concrete composite test block was laid on the roof,the average daytime temperature of the test block decreased by 1.13? due to heat storage and water evaporation;(2)compared with the container without any treatment on the roof,the total energy consumption of the whole day reduced by 2% after the porous phenolic-concrete composite test block was laid on the roof.4.The differences of passive evaporative cooling and energy saving between porous phenolic-concrete composite test block and porous phenolic-coated earthen roof were compared by using container test room,and the reasons for the differences and the advantages and disadvantages of porous phenolic-coated earthen roof were analyzed.The conclusion shows that: taking the experimental data of 27 days as an example,the power consumption of the phenolic soil test room is 4.489 kw in the daytime,the power consumption of the phenolic soil test room is 0.183 kw higher than that of the blank test room,and the power consumption of the phenolic soil test room is 0.269 kw higher than that of the phenolic composite test room.