Characterization of Insulation Performance, Poststability, and Foaming Process of Rigid Polyurethane Sandwich Panel for Cold Storage Warehouse

Jie Xu,Chuang Peng,Wei Sun,Tao Wu

doi:10.1061/(asce)mt.1943-5533.0001984

Abstract

Polyurethane (PU) is a commonly used insulation material for cold storage warehouses. The insulation performance of PU sandwich panels made from blended blowing agents were re-assessed by k-factor measurements and insulation thickness calculation based on cold warehouse design standard, which has proved the significant impact of blowing agent difference on energy saving. The foam post-stability was also evaluated by mathematic profiling. The developed 3D paraboloid model based on gridding measurements has provided scientific method for panel shrinkage evaluation. Cell microstructure characterization and post-growth angle coefficients calculation were further performed for better understanding the shrinkage problem at microscopic level. The foaming process model of continuous panel production was developed based on FOAMAT characterization which has provided theoretical solution to panel processing.

Highlights

Insulating materials with extremely low thermal conductivity (< 0.03 W/m.K) are commonly used for cold storage
Thermal conductivity λ, known as k-factor, defines the steady state heat flow passing through a unit area of a homogeneous material, 1 m thick, induced by a 1 K difference of temperature on its faces, which is expressed in W/mK and can be measured in compliance with EN 12664 (EN 12664. 2001), EN 12667 (EN 12667. 2001), EN 12939 (EN 12939. 2000) and ASTM C518 (ASTM C518-10)
Thermal transmittance, known as U-Value, defines steady state heat flow passing through a unit surface area induced by a 1 K difference of temperature which takes into account the convective and radioactive heat transfers, which is expressed in W/m2K and can be measured with the hot-box method (EN ISO 8990; EN 12567-1; Asdrubali et al 2011; Baldinelli et al 2014) or calculated by ISO 6946 (ISO 6946)

Summary

Introduction

Insulating materials with extremely low thermal conductivity (< 0.03 W/m.K) are commonly used for cold storage. The heat flow through cold surface is produced by vapour condensation over pressure gradient created by ambient air passing through the walls This condensation is subject to cell gas freezing point and attributes to the materials conductivity. High performance PIR panels for cold warehouse use made of HFC-245fa blowing Thermal performance is one of the key properties for insulation material which can be measured in two different conditions: unsteady state and steady state. Post-cure stability, a combination problem of post-expansion (inflation) and post-shrinkage (deflation), is one of the key performance measurements to polyurethane foam materials for cold storage warehouses use. Such foam volumetric changes start right after panels coming down from the production line and end when heat transfer over temperature gradient diminishing. Panel post-stability control is critical to cold warehouse building quality management

Methods

Results

Conclusion