Exergy Analysis Of Evaporative Cooling And Numerical Research On The Heat Transfer In A New Plate Heat Exchanger

Exergy analysis is applied on evaporative cooling. A quasi-counterflowPlate heat exchanger with hexagonal dividing plates is proposed for indirectheat exchange and evaporative cooling. Numerical simulation is used toanalyze three-dimensional flow and heat transfer processes.In Chapter 2, research on principles of exergy anaIysis in air-conditioninglead to a new selection of dead-state and proper evaluation of air-conditioningprocess with exergy effectiveness and exergy efficiency ratio.The conversion of available energy in different evaporative coolingprocesses is analyzed and evaluated in Chapter 3. As results, exergy of moistair is suggested to be evaporative cooling potential and regenerativeevaPorative cooling will be most potential in effectively utilizing the availableenergy.ln ChaPter 4, imbalanced counterflow of indirect evaPorative cooling issimulated while taking into account the non-linearity of the saturation line ofmoist air. Four diagrams are provided to assist in determination of theoptimum heat caPacity ratio.Chapter 5 and ChaPter 6 deal with the physical and mathematical modelfor the proposed heat exchanger. Numerical schemes are discussed in detail. AproPbr data structure is used to assist grid generation for different geometricdimensions.A concept of entropy in broad sense is proposed for convective-diffusiveproblems in ChaPter 7. It is proved that there is an intrinsic relationshipbetween the stability of the numerical schemes of the convective--diffusivedifferential equations and the non-negative property of the entropy generationcaused by the effective diffusion. Thus, non-negative property is suggested asthe criterion of stability. Furthef, diffusion coefficient is replaced by anartificial one in the finite difference equation to simulate the entropygeneration can improve the accuracy of the numerical analysis.ln Chapter 8 and ChaPter 9, numerical analysis is validated byexperiment. Flow structure and heat transfer is analyzed numerica1ly. Anequation of effectiveness is correlated with heat transfer units, Reynoldsnumber, and geometric ratios.