air Property of air

The refrigeration of beef carcasses is an important user of energy. Due to the carcass's complicated shape and composition, it is difficult to calculate the rate of heat release as it evolves with time during the cooling process. A method has therefore been devised to measure the latent, sensible and radiative heat loads from beef sides. The latent heat load is measured within 3 % error by suspending the beef side on a load cell measuring to ± 0.15 ppm. The sensible and radiative heat load is measured within 5 % error using a flow-calorimeter type movable wind tunnel constructed to hold one beef side. Due to the small magnitudes of the weight losses, relatively large fluctuations in the weight loss curve occurred and it was necessary to smooth the curve by curve-fitting a three-parameter equation, using an evolutionary algorithm. Typical results are shown. These results are much more precise than results obtained earlier with compensatory heating methods. NOMENCLATURE a,b,c Parameters in the weight loss equation cp Specific heat capacity of air (J/kgK) ∆T Temperature change over product (K) ∆V Voltage difference across thermopile (mV) hfg Latent heat of vaporisation (J/kg) M Mass flow rate (kg/s) q Product heat load (W) RH Relative humidity (%) t Time (s) W Cumulative weight loss (kg