Study On Thermal Insulation Efficiency And Structural Style Of Quasi-high Show Case

With the rapid economy development of our country, the improvement of people's standard of livings, the acceleration of rhythm, freezing and cold-stored's foods take on a flourishing vision. The development of freezing and cold-stored's foods boosts food's refrigeration's more advances. Display case is the important part of refrigeration chain and is accordingly progressed in these years. Especially quasi-high show case is favored by client, because of its beautiful appearance and the particular effect of lay out.This paper analyzes quasi-high display case airstream's flow field in detail, indicates that heat infiltrating air curtain mostly accounts for total heat load , that the improvement of air curtain closure will reduces spillage .This paper introduces directed simulation ,large -eddy simulation and Reynolds time averaged simulation including k-ε model as well as Reynolds stress model, chooses k~s model to simulate after comparing them .According to the characteristics of quasi-high case, physical model and calculating field, etc, are developed, the important elements that affect air curtain performance such as environmental temperature and humidity , bluing-in velocity and temperature ,turbulence scale of bluing in, wind valley fabric ,are analyzed. Blowing in velocity of air curtain is the most important factor. The paper studies on two kinds of blowing in velocity(0.9 and 1.1m/s)impacting on temperature distribution and flow field of air curtain by experiments, detects, to quasi-high case ,air curtain has a deflection towards inside due to heat press led by inward-outward temperature difference .Big velocity of returning air is formed in wind returning valley ,some cool air is escaped from show case due to inertia .The smaller velocity is ,the more poor air curtain closes ,it is because air velocity can't overcome environmental air turbulence. The bigger velocity is, the bigger air curtain gets inertia and the smaller deflection angel as well as cool air leakage. Optical closing ability of air curtain can be made by adjusting air velocity.The paper concepts optimizational design of quasi-high show case, considers installing an air damper (150 mm .high) in air returning valley will effectively keep air curtain from escape, and have little impact on appearance of show case, with is a effective way to save energy .The improvement of air-curtain's efficiency is validated by simulating calculation and experiments.