108 Meat refrigeration Table 6.4 Ratio of the peak to the average rate of heat release from 140 kg beef sides, for chiller cycle time of 24 h from I h post-mortem Chiller conditions ak to average ratio Air speed (ms) Temperature Loading period C 0.5 2.0 3.0 3.4 04040404 22446688 4433 33025834 4.3 3.0 6 2.3 2.5 Source: Cox and Bailey, 1978 Table 6.5 Ratio of actual to average heat load ratios for 140 kg beef side in air at0C, 1.0ms", for a chiller cycle time of 24 h from Ih post-mortem Time after start Heat load ratios at Time after start Heat load ratios at of chill (h end of period shown of chill (h) end of period shown 6 46802 0.8 0.3 Source: Cox and Bailey, 1978 Peak load data charts have also been produced in South Africa(Kerens, 1981) for two air temperatures (0 and 7C), an air velocity of 0.75ms and 95% relative humidity. They are expressed in terms of peak heat loss rate against a loading rate in cattle units per hour. A cattle unit is defined as a whole carcass and the average whole carcass weight is 210kg In a typical South African situation a plant operating at 0C, 0.75ms would be loaded over a 3 h period at a rate of 200 cattle units h". The peak heat loss rate from the 600 carcasses would be 550kw. It is stated that using three chill rooms, each with a capacity of 200 carcasses(400 sides), the fan powe required would be 60kw and the heat infiltration 105kw, of which 90k infiltrates through the doors. Thus, the total peak load on the refrigeration plant would be 715kw 6.2.1.4 Cost of chilling operation Data were obtained from a survey of 14 commercial beef chilling systems (Gigiel and Collett, 1990). They ranged in capacity from 18000 to 93000kgPeak load data charts have also been produced in South Africa (Kerens, 1981) for two air temperatures (0 and 7 °C), an air velocity of 0.75 m s-1 and 95% relative humidity. They are expressed in terms of peak heat loss rate against a loading rate in cattle units per hour. A cattle unit is defined as a whole carcass and the average whole carcass weight is 210kg. In a typical South African situation a plant operating at 0°C, 0.75 m s-1 would be loaded over a 3 h period at a rate of 200 cattle units h-1 . The peak heat loss rate from the 600 carcasses would be 550 kW. It is stated that using three chill rooms, each with a capacity of 200 carcasses (400 sides), the fan power required would be 60 kW and the heat infiltration 105 kW, of which 90 kW infiltrates through the doors. Thus, the total peak load on the refrigeration plant would be 715 kW. 6.2.1.4 Cost of chilling operation Data were obtained from a survey of 14 commercial beef chilling systems (Gigiel and Collett, 1990). They ranged in capacity from 18 000 to 93 000 kg 108 Meat refrigeration Table 6.4 Ratio of the peak to the average rate of heat release from 140 kg beef sides, for chiller cycle time of 24 h from 1 h post-mortem Chiller conditions Peak to average ratio Temperature Loading period Air speed (m s-1 ) (°C) (h) 0.5 1.0 2.0 3.0 0 2 3.4 3.3 4.3 4.0 4 2 4.1 3.7 4.3 4.3 0 4 2.9 2.8 3.0 3.0 4 4 3.1 2.7 3.2 3.1 0 6 2.5 2.5 2.5 2.6 4 6 2.7 2.3 2.8 2.7 0 8 2.3 2.5 2.3 2.4 4 8 2.6 2.3 2.4 2.5 Source: Cox and Bailey, 1978. Table 6.5 Ratio of actual to average heat load ratios for 140 kg beef side in air at 0 °C, 1.0 m s-1 , for a chiller cycle time of 24 h from 1 h post-mortem Time after start Heat load ratios at Time after start Heat load ratios at of chill (h) end of period shown of chill (h) end of period shown 2 3.3 14 0.6 4 2.3 16 0.4 6 1.5 18 0.4 8 1.2 20 0.4 10 0.8 22 0.3 12 0.7 Source: Cox and Bailey, 1978