A 50-kg box of beef at 8 C having a water content of 72 percent is to be frozen to a temperature of -30 C in 4h. Freezing point is at -2 C. Specific heat of the beef above freezing is 3.23 kJ/kg.K and below freezing is 1.5 kJ/kg.K. Determine (a) the total amount of heat that must be removed from the beef, (b) the average rate of heat removal from the beef.

A 50-kg box of beef at 8 C having a water content of 72 percent is to be frozen to a temperature of -30 C in 4h. Freezing point is at -2 C. Specific heat of the beef above freezing is 3.23 kJ/kg.K and below freezing is 1.5 kJ/kg.K. Determine (a) the total amount of heat that must be removed from the beef, (b) the average rate of heat removal from the beef.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.12P

See similar textbooks

Similar questions

1.60 Two electric resistance heaters with a 20 cm length and a 2 cm diameter are inserted into a well-insulated 40-L tank of water that is initially at 300 K. If each heater dissipates 500 W, what is the time required for bringing the water temperature in the tank to 340 K? State your assumption for your analysis.
2.55 A long, 1-cm-diameter electric copper cable is embedded in the center of a 25-cm-square concrete block. If the outside temperature of the concrete is 25oC and the rate of electrical energy dissipation in the cable is 150 W per meter length, determine temperatures at the outer surface and at the center of the cable.
2.34 Show that the temperature distribution in a sphere of radius . made of a homogeneous material in which energy is released at a uniform rate per unit volume , is
2.44 To determine the thermal conductivity of a long, solid 2.5-cm-diameter rod, one half of the rod was inserted into a furnace while the other half was projecting into air at . After steady state had been reached, the temperatures at two points 7.6 cm apart were measured and found to be and , respectively. The heat transfer coefficient over the surface of the rod exposed to the air was estimated to be 22.7 . What is thermal conductivity of the rod?
Determine the heat extracted(in KJ) from 2000 kg of water from 25°C to ice at -10°C.
A 50-kg box of beef at 8°C having a water content of 72 percent is to be frozen to a temperature of -30°C in 4 hours. Freezing point is at -2°C. Specific heat of the beef above freezing is 3.23 kJ/kg.K and below freezing is 1.5 kJ/kg.K. Determine (a) the total amount of heat that must be removed from the beef, (b) the average rate of heat removal from the beef.
In a ball bearing production facility, steel balls (k=50 W/m.K, c=0.460 kJ/kg.K, ρ=7865 kg/m3) that are each of 13,99 mm in diameter are annealed by first heating them to 870 oC and then slowly cooling in air to 125 oC. If the cooling air stream temperature is 60 oC, and it has a convective heat transfer coefficient of 35 W/m2.K), determine the time [s] required for the cooling.
Cold salt brine at -2°C is used in a packing plant to chill food slabs from 40°C to 3.4°C in 18 hours. Determine the mass of brine required to cool 100 food slabs of 225 kg each if the final temperature of the brine is 1.7°C.
In an experimental set-up, 5 kg of salt solution is heated in a glass vessel by a gas burner. An electric stirrer is used to ensure uniform heating of the solution. The internal energy of the solution is to be increased from 200 to 250 KJ/kg in 15 minutes. The power consumption of the stirrer is 30 W. The rate of heat loss from the vessel is 50W. Determine the power of the gas burner required.
Three tons of fish is to be stored at a temperature of -10°C for 24hrs. The product enters the chiller at a temperature of 8°C. The specific heat below and above freezing is 0.41 kcal/kg-C and 0.76 kcal/kg-C respectively and its latent heat of fusion is 51 kcal/kg. If the freezing temperature of the product is -2.2 °C, determine the product load in kcal/hr.
The inner and outer surfaces of a 0.5-cm-thick 2-m × 2-m window glass in winter are 15°C and 6°C, respectively. If the thermal conductivity of the glass is 0.78 W/m·°C, determine the amount of heat loss, in kJ, that occurs through the glass over a period of 10 h. What would your answer be if the glass were 1 cm thick?
In a manufacturing facility, 2-in-diameter brassballs (k = 64.1 Btu/h·ft·°F, r = 532 lbm/ft3, and cp =0.092 Btu/lbm·°F) initially at 250°F are quenched in a waterbath at 120°F for a period of 2 min at a rate of 120 ballsper minute. If the convection heat transfer coefficient is42 Btu/h·ft2·°F, determine (a) the temperature of the balls afterquenching and (b) the rate at which heat needs to be removedfrom the water in order to keep its temperature constant at120°F.