It is a common experience to feel 'chilly' in winter and 'warm' in summer in our homes even when the thermostat setting is kept the same. This is due to the so-called 'radiation effect' resulting from radiation heat exchange between our bodies and the surrounding surfaces of the walls and the ceiling. (a) Briefly discuss another ONE heat transfer mechanism between the human body and the environment in maintaining healthy human body temperature at 37°ċ while the temperature and the humidity of the environment change with time. (b) Explain how a person can keep cooler in summer and warmer in winter. (c) Consider a person whose exposed surface area is 1.7 m2, emissivity is 0.5, and surface temperature is 32°C. Determine the rate of heat loss from that person by radiation in a large room having walls at a temperature of two situations of 280 K and 300 K. Use Stefan-Boltzmann constant as 5.67 x 10-8 W/m2-K*.

Example • The cylinder is made from aluminum with diameter and thickness of 5 cm and 1 cm respectively. The wall temperature in the inside of cylinder is 50°C, while the temperature of the air is 30°C. the coefficient of convection in the air is 10 W/m2-C. Calculate the heat loss from the cylinder per unit length! • Calculate the thickness of the insulation so heat loss from cylinder will decrease 50% of initial condition. Thermal conductivity of the isolator (k) : 0.5 W/m°C state.pptx 7 MB VIEW Tampilkan semua

A copper electric wire of radius R, = 1 mm is isolated by a layer of PVC so that the outer radius of the wire Rg = 2 mm, as shown in Figure below. The wire exchanges heat with the air at 20°C according to a heat transfer coefficient h=20 W/m2°c: Given that : k=copper electrical conductivity=4.0 × 1070hm-'m¯! kpvc= PVC thermal conductivity = 0.3- m°C kco = copper thermal conductivity = 100 m°C %3D (amp/m)² And that the electrical heating source is given by : S, amp²s /kgm³ If the temperature (T,) on the outer surface (r = RG) is 25°C, what is the electrical current C (amp) that passes through this wire? Dont forget to state your hypothesis clearly.     Hi, Could you please tell me what the book's name is? Thank you!

In a movie theater in winter, 500 people are watching a movie. The heat losses through the walls, windows, and the roof are estimated to be 150,000 Btu/h. Determine if the theater needs to be heated or cooled.