Experimental analysis of refrigerated truck thermal behaviour

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.This study mainly focuses on experimental investigation of ceiling-slot ventilated enclosures for determining the airflow and thermal characteristics. The experimental prototype has the dimensions of 8.33 m (length) x 2.50 m (height) x 2.46 m (width) and the cooled air is injected into the container through a half-width slot positioned at the centre of front surface and close to the ceiling. The prototype is positioned inside of a climatic test chamber having dimensions of 14 m (length) x 5 m (width) x 6.5 m (height). The temperature and the relative humidity of the test chamber may be varied within limits of (- 20°C and +50°C), and (5% and 95%) respectively. The air velocity at the slot exit is varied by changing the fan speed so that two different Reynolds numbers 4.3x105 and 7.86x105 are studied in the analysis. In experiments, the system at specified inside, outside and airflow conditions is approximately run for two hours to establish steady-state conditions. In recording data, the system data is divided into two groups: 1. The cooling unit data that includes refrigerant side volumetric flow rate, the pressure and temperature at the inlet and outlet of compressor, condenser and evaporator. Additionally, temperature and volumetric flow rate of air through the condenser, and the fuel consumption of the engine are also recorded. 2. The container data covers air velocity at the slot exit, and a total of 110 thermocouples measure the surface temperatures of all surfaces (inside and outside) of the container and local temperature variation of the airflow. Measurements carried out at both sides (air side and refrigerant side) to validate the data with an accuracy band ±6.5% of the air side measurements. The thermal performance of ventilation in the container is measured by a non-dimensional temperature distribution, θx at a particular cross-section. As a result of measured data, conventional COP of the system and f COP based on fuel consumption rate are also presented.