Vacuum insulation panels for refrigerators

Abstract

Globally, the electrical energy consumption of domestic refrigerators is approximately 6% of the total consumed. Typically, refrigerators are insulated with materials, such as foams (thermal conductivity >20 mW m-1 K-1). Alternatively, using Vacuum Insulation Panels (VIPs) (thermal conductivity < 7 mW m-1 K-1) would significantly reduce their overall energy consumption and improve their energy efficiency index whilst maximising the usable inner volume. This paper reviews previous published research into VIPs covering core, envelope, heat transfer phenomena and ageing. The choice of core material significantly affects both the heat transfer coefficient and the overall cost of a VIP. To improve cost effectiveness and ageing properties, research has focused on the development of alternative core materials. This development requires a fundamental understanding of the effect of several interfering factors on the performance of VIPs. In this paper, these factors have been extensively reviewed and the results presented in a systematic manner. The factors are grouped into three sections viz. material properties (pore/particle size, particle's mechanical strength and conductivity), design properties (sealing pressure, compaction density) and operating conditions (mean operating temperature, relative humidity). The effect of each factor, on heat transfer modes, radiation and conduction, has been thoroughly discussed, along with the physics involved, by objectively reviewing studies reporting these.

Temperature characteristics of a wood-insulated refrigeration system for chilling and preservation of agricultural products

“…Insulation plays a vital role in the effective operation of refrigeration systems, and there exist various advancements in insulators used in refrigerators. Some of them include aerogel [7], polystyrene foam [8], glass wool [9][10][11], thermocol [11], as well as vacuum insulation panels, polyurethane foam, polyethylene terephthalate foam, and natural fiber insulation [12]. Vacuum insulation panel is made up of a core material surrounded with a gas-tight barrier, minimizing heat transfer, and thereby leading to good insulation.…”

Vacuum Insulation Panels for Thermal Energy Storage Systems

“…Vacuum insulation panels, or VIPs, are insulations which have the ability to provide a thermal conductivity value of 4 mWm -1 K -1 at room temperatures, which is around 10 times lower than glass wool's thermal conductivity. VIPs consist of a porous core material made of powder / fibers / foam which is evacuated to pressures ranging from 1 mbar to 0.1 mbar and sealed in a polymer / metal based envelope [3,4].…”

“…Vacuum insulation panels (VIPs), which are increasingly being used in cold chain equipments like refrigerators, cold storage boxes etc. [3,4] could also be effective to suppress the heat losses from TES tanks, due to their extremely low thermal conductivity (0.004 W m -1 K -1 at room temperature) [5]. In the present work, we developed a computer model to compute the rate of heat loss from a hot TES tank throughout the day, with varying ambient temperature, including its charging and discharging processes.…”

The Green Logistics Idea using Vacuum Insulation Panels (VIPs)

“…Cold storage insulators have been continuously developed from the past to the present. The progressing of cold room insulators, as shown in Figure 2 [4]. Found that, the best heat transfer coefficient (U value) value is vacuum insulated panels (VIPs) [5] and smallest size [6].…”

“…Therefore, VIPs is appropriate to be used in this research to reduce the heat load, reduce energy consumption and maintain the quality of the product [7]. [4] The logistics model uses a frozen truck with the temperature at -25 to -23 degrees Celsius, chiller trucks 0 to -2 degrees from the factory to the distribution center, and end-user. The type and size of rucks in this model will differ from length to the destination or product type.…”