Temperature Waves Phase Optimal Time Lag in the Refrigerated Warehouse Thermal Insulation

Abstract

The thermal inertia of the wall manifests itself as a damping of amplitude (Decrement Factor) as well as a temperature wave phase lag (Time Lag) upon its passing through the wall. The objective of the research was to highlight the utilization prospects of these phenomena in the building envelops of large refrigerated warehouses. Numerical methods were used for nonlinear, non-stationary processes simulation. The relationship of the refrigeration cycle to the thermo-insulating walls of the cold store in the conditions of daily external temperature oscillations and solar radiation flux has been studied. As the ambient temperature rises, the power efficiency of the refrigeration cycle is decreasing and the need to increase the compressor displacement is growing. If the value of the phase delay in the wall is optimum, the daily minimum of the heat leakage through the wall enters the chamber with the phase shift for the period of maximum daily external temperature. This enables to smooth out the daily oscillations amplitudes of the heat load of the refrigerating machine as well as compressor power rating and to approximate their peak values closer to the average daily ones. The study had been concluded by demonstrating the possibility of reduction in: heat exchange areas for both condenser and evaporator, receiver volume, diameter of pipelines, material cost. Better conditions for temperature stabilization in the cold store will enhance the keeping quality and prolong the food products shelf life.