A mectal cylinder of 5 cm in diameter and initially at a temperature about 150 °C. the eylinder is suddenly immersed in liquid with temperature at 50 °C and heat transfer coeflicient about 2000 W/m.°C. Under typical operation conditions the center temperature and surface temperature are measured to be 110 °C and 90 °C after 1 minute, respectivielly. Calculate the thermal conductivity for this material.

The surface of a furnace wall is at a temperature of 1200°C. The outside wall temperature is 38°C. The furnace wall construction has 15 Cm of refractory material,), k = 1.73 W/m-K., and the outside wall is 1-cm steel, k = 44 W/m-K. What thickness of refractory brick must be used between the refractory material and the wall if the heat loss is not to exceed 0.7 kW/m2? The thermal conductivity of the brick is 0.34 W/m-K.

A long solid rod of 20 mm diameter was inserted into a furnace while the other end was projecting into atmosphere at 28°C. The temperature at two points 100 mm apart were measured and found to be 125°C and 91°C respectively. Estimate the thermal conductivity of the rod, if heat transfer coefficient is 17.45 W/m?K.

Calculate the heat transfer per hour through a solid brick wall 6 m long, 3 m high, and 240 mm thick, when the change in temperature is equal to 15 C, the coefficient of thermal conductivity of the brick being 0.6 W/m-K.

Don’t use Heissler charts to answer this question   Heat sterilization of lumber, timbers, and pallets is used to kill insects to prevent their transfer between countries in international trade. This is analogous to food sterilization by heat. A typical requirement here is that the slowest heating point of any woodconfiguration be held at 56 °C for 30 minutes. Consider hot air heating of wooden boards that maintains their surface temperature at 70 °C. The boards are stacked outside and in the winter time they can be considered to be at 0 °Cwhen theyare brought in for heating. The thermal diffusivity of the wood is 9*10-8m2/s.   a.Calculate the time from the start of heating for a 2.5 cm thick board to reach a sterilization temperature of 56 °C at its slowest heating point .b.Calculate the heating time when four such boards are stacked together. c.Calculate the ratio of the two heating times (for a single board versus when they are stacked), and explain the ratio. Note: You’re free to…

A piece of beef steak 7 cm thick will be frozen in the freezer room -40 ° C. This product has a moisture content of 73%, a density of 970 kg / m³, and a thermal conductivity (frozen) of 1.1 W / (m K). Estimate the freezing time. using the Plank equation. This product has an initial freezing temperature of -1.75 ° C, and the movement of air in the freezing room gives a convective heat transfer coefficient of 15 W / (m² K). t f = Answerhour.

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A slab of meat 25.4 mm thick originally at a uniform temperature of 10 ℃ is to be cooked from both sides until the center reaches 121 ℃ in an oven at 177 ℃. The convection coefficient can be assumed constant at 25.6 W/m2.K. Neglect any latent heat changes and calculate the time required. The thermal conductivity is 0.69 W/m.K and the thermal diffusivity 5.85 x 10-4 m2/h. Use the Heisler chart. Answer:0.8 h

A closed container filled with hot coffee as shown below is in a room whose air and walls are at fixed temperature much lower than the coffee. Identify all heat transfer process that contributes to cooling of the coffee. Draw schematics, make necessary assumptions (black body, thickness, materials and convection coefficient) and find the heat flux equation and temperature equation at points of heat transfer. Hot coffee Cover Air space Plastic flask

Number 3 A food product with 80% moisture content in a 7 cm diameter can wants to be frozen. The density of the product is 1000 kg/m³, the thermal conductivity is 1.0 W/(m²K), and the initial freezing temperature is -1.75°C. After 8 hours in the freezing medium -25°C, the product temperature becomes -10°C. Estimate the convection heat transfer coefficient of the freezing medium. Assume the can as an infinite cylinder. h= answer in W/(m²K)