Question

ASSIGNMENT 1 Example below was discussed in class The roof of an electrically heated home is 6 m long, 8 m wide, and 0.25m thick, and is made of a flat layer of concrete whose thermal conductivity is k = 0,8 W/m.K. The temperature of the inner and the outer surfaces of the roof one night are measured to be 15°C and 4°C, respectively for a period of 10 hours. Determine (a) The rate of heat loss through the roof that night. (b) The cost of that heat loss to the home owner if the cost electricity is $0.08/kWh. You are not required to answer the above question. TASK Create a question on heat transfer that describes situation in Malaysia. Below are some examples for your references. You can also make your own original question (highly recommended) but still need to describe situation in Malaysia. Example : air-conditioned home on a hot day, or wooden house (thermal conductivity of wood), or glutinous rice cooked in bamboo (lemang), etc.... And DO NOT forget to answer the question.

Answer 1

Page No Created question: Ouy. An air-conditioning system in Malaysia during hot and humid day is to take in air at I atm 34°c, and 70% sulative humidity and deliver it at ddec omd 50%. selative humidity. The air flow first over the cooling coil, where it is cooled and dehumidified, and then over the resistence heating wire, where it heated to the desired temperature. Assuming that the condensate is removed from the cooling section at loc, determine the temperature of air before it enters the heating section, the amount of heat removed in the cooling section in ks/ lg dry cur. & heating of Solution weer Ta V Cooling rections Section elleu ہ I atm Ais T3 =22°C 3=50/ 0 0 0 10°c water for steady state state mass mass flow flow rate of dry air will be constant mag = maz = mal =ma W3 =Wg 08=100% DBT CS Scanned with CamScanner

state & wat Stute & DBT = 34°C 34°c 0= 7098 page No@ hi= 95.2 kJ llg W = 0.0338 kg / Hg of dry air state 3 DBT = 22°C $3 = 50% h3 =-43*1 kolig 50.0082 kg llg of dry air at mixture saturated 0=100 h W q =W3 hož hf = 42 kJ / 1g at T= 10° come pressure = 1 atm from steem table Wa =W3=0.0082 kg 1 kg of dry air therefore -0.0089 g Ilgof c (DBT line at wg =W3 pa Ayos drycin =100% Now performing Energy Belence, Ein (for steedy State) Ein = Cout Emh) ast (m how it mwhwn Bout cooling = (min)o, 2 +(min) wiz miah, who Sout mana zo Chichal hง = 6-c02) Te = liitºc TO ). Eout = Af System AF = 0 Tour - Bout - ) In mw ma ma ma Yout= (ho-hg)-(w, was hw -195.2 - 3110) -(0.0238 -0.0082)X42.02 Yout = 62.7 kol lg dry air CS Scanned with CamScanner