This paper presents theoretical and experimental studies on the stratification decay in stratified storage tanks. The effects of the thicknesses of tank wall and thermal insulation were discussed. The experimental results showed that the outside insulation can enhance tank wall axial conduction which tends to degrade the stratification. However, the reduction of heat loss outweighs the enhancement of axial conduction and better stratification is still maintained when compared to a bare wall tank. The axial conduction enhancement is sensitive to the wall thickness for the same thickness of insulation, however, it is not strongly dependent on the insulation thickness for identical thick wall. The addition of inside insulation is helpful in preserving stratification. A two-dimensional laminar flow model was also developed to interpret the temperature and flow fields inside storage tanks and the numerical results were compared with the experimental data.
Rigid polyurethane foam is one of the most effective practical thermal insulation materials used in applications ranging from buildings to the domestic refrigerator. However, owing to the need to eliminate the CFC blowing agents that are hazardous to the environment, an advanced insulation must be developed. One of the most effective forms of thermal insulation, as employed in the walls of the refrigerator, is the vacuum insulation panel (VIP). VIP insulation consists of the core materials that are encapsulated at low pressure in a very thin, low gas permeability and low conducting barrier. This paper focuses on a unique panel design based on the evacuated, 100% open cell rigid polyurethane foam with getters encapsulated in laminated films under various conditions. A series of studies of the effect-factors of the batch manufacture efficiency and the thermal conductivity performance of the VIPs are discussed. Those effect-parameters are rigid polyurethane foams cell size, drying pretreatment, evacuation pressure, with or without getters and encapsulation barrier.
Vacuum insulation panel (VIP) consists of the core materials that were encapsulated at low pressure in a very thin, low gas permeability and low conducting barrier. The paper presented herein focuses on a unique panel design based on the evacuated 100% open cell rigid polyurethane foam with getters encapsulated in laminated films under various conditions and the application of VIPs. A series of studies of the effect of the batch manufacture efficiency and the thermal conductivity performance of the VIPs was discussed. In this study, several pieces of VIPs were installed on the walls of a refrigerator, show-case and refrigerator vehicle cabinet to evaluate the energy efficiency by measuring the heat loss. Heat loss from a cabinet located in an environmental room was measured by a reversed heat leak method under testing conditions. The results show heat loss energy efficiency improving over 25% for mounting the VIPs on the refrigerator and the reverse heat leak is improved by 8.0% and 28.9% for the refrigerator vehicle cabinet and showcase, respectively
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