Design a spherical tank, with a wall thickness of 2 cm that will assure that no more than 50 kg of hydrogen will be lost per year. The tank, which will operate at 500 °C, can be made of nickel, aluminum, copper, or iron. The diffusion coefficient of hydrogen and the cost per kg for each available material is listed here.

A cylindrical container is being designed to contain an exothermic chemical reaction. The container has an external diameter of 80 mm and is 0.2 m tall. The temperature of the cylinder must not exceed 500 °C. To improve cooling of the container, fins of thickness t=5 mm and length L= 40 mm are spaced at least 10 mm apart. Each fin has an efficiency of n= 40%. The ambient temperature is maintained at 22 °c and the heat transfer coefficient between the ambient air and the cylinder is 50 W/m2K. If the chemical reaction produces a maximum of 3.2 kW per kilogram of substance, the maximum mass of substance which can safely be processed in the container to 2 decimal places is kg. The effectiveness of each fin to 1 decimal place is You may neglect heat transfer from the tips of the fins and from the circular surfaces of the cylinder.

a piece of beef steak 7 cm thick will be frozen in the freezer room -40 degrees Celsius This product has a moisture content of 73% density 970 kg / m³ and a thermal conductivity of 1.1 W / (m K) frozen using the plank equation. This product has an initial freezing temperature of -1.75 degrees Celsius and the movement of air in the raw chamber gives a convection heat transfer coefficient of 10 W / (m² K). tf =

A food product wants to be produced in a small round shape (pellet) by freezing it in a water blast freezer freezer. Air freezer operates at -30 ° C. The initial product temperature is 25 ° C. The pellet has a diameter of 1 cm, and a density of 980 kg / m³. The initial freezing temperature is -2.5 ° C. The latent heat of freezing of the product is 280 kJ / kg. The thermal conductivity of the frozen product is 1.9 W / (m ° C). The convective heat transfer coefficient is 40 W / (m² K). Calculate the freeze time. t f = Answerhour.