Experimental Investigation On Enhanced Heat Transfer Of Nanofluid Flow Through Mini-channel Jackets

With the improvement of integration technology,facilities for chemical en-gineering and the food change into smaller.The smaller the facility,the larger heat flux.Heat exchangers with appropriate size,less weight,and high efficient must be employed to meet the change.Secondary flow caused by fluid flow in curved micro channel/mini channel which are applied in different facilities could enhance heat exchange.Moreover,it is a valid method to enhance heat transfer performance of smaller heat exchanger by substitute nanofluid with higher heat transfer coefficient for traditional heat transfer working medium.The paper experimentally investigates characteristics of heat transfer and liquid fluid flow in two different mini-channel jackets with different fluid work-ing medium.Experimental liquid medium are TiO2-deionized water nanofluid with/without dispersant for 0.05%and 0.1%weight concentration and pure de-ionized water.Analyzing contrastively the effect of nanoparticle weight concen-tration on heat transfer and flow in curved mini channels jackets.Besides,repet-itive experiments would be carried out in comparison to base liquid by inves-tigating the characteristics of heat transfer and fluid flow of deionized water run in jackets which were uncleaned/cleaned after the experiments of nanofluid flow in jackets.The main results are following as:1)in the case of helical mini-channel jackets,the increase of enhanced surface friction fraction f is at-tributed to the improvement of nanoparticle weight concentration and the addi-tion of dispersant put into nanofluid.For all nanofluid run in helical mini-jacket,the experiment of 0.05%weight concentration nanofluid with dispersant has the best heat transfer performance but the experiment of 0.05%weight concentra-tion nanofluid without dispersant is opposite.The average Nusselt number for nanofluid flow in helical jacket of 0.1%nanoparticle weight concentration are almost same whether the dispersant is put.The average Nusselt number and sur-face friction fraction f by repetitive experiment for deionized water flow in heli-cal mini-jacket are bigger than that for based liquid.It should be noticed that the average Nusselt number and surface friction fraction f for repetitive experiments after cleaning jacket and experimental loop are greater than that before cleaning jacket and experimental loop.Performance evaluation criterion of the 0.05%weight concentration nanofluid with dispersant is the best among all nanofluid run in helical mini-channel jacket.However,the repetitive experiment operated behand cleaning the experimental loop and jacket after the experiment of 0.05%weight concentration nanofluid has the best performance evaluation criterion for repetitive experiments.2)The dispersant could increase average Nusselt number and drop pressure between inlet and outlet of nanofluid flow in circumference parallel curved mini-channel jacket.It is worth noting that the average Nusselt number and drop pressure between inlet and outlet of nanofluid with/without dispersant flow in circumference parallel curved mini-channel jacket is not greater than that for base liquid.The average Nusselt number and drop pressure between inlet and outlet for repetitive experiments after cleaning jacket and ex-perimental loop are greater than that before cleaning jacket and experimental loop.Nevertheless,drop pressure obtained by repetitive experiments are more than base liquid and the average Nusselt number obtained by repetitive experi-ments is on the contrary.Performance evaluation criterion of the experiment us-ing 0.05%weight concentration nanofluid with dispersant is the best among all nanofluid run in circumference parallel curved mini-channel jacket.However,the repetitive experiment operated behand cleaning the experimental loop and jacket after the experiment of 0.05%weight concentration nanofluid has the best performance evaluation criterion for repetitive experiments.Some theoretical equations for predicting the Nusselt number and surface friction coeffcient f of liquid working medium flow through helical mini-channel jacket and circum-ference parallel curved mini-channel jacket have been presented respectively.