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GANDHI INSTITUTE OF TECHNOLOGICAL ADVANCEMENT 2 nd INTERNAL EXAMINATION (Additional) Sub:Refrigeration & Air Conditioning F.M.:20 Sem:7 th semester Branch:Mechanical Engg. (Answer all the question of Q. No. 1 & any two from the rest of the question) 1. (a)Write any five physical & chemical properties of Refrigerants ? (b)Why freons expected to be phase out as refrigerants? Which are. Eco- friendly replacement refrigerant being tried? (c)Define room sensible heat factor. How room sensible heat factor line is drawn on psychometric chart? (d)On a particular day the weather forecast states that the DBT is 37 0C ,while the RH-50% & the barometric pressure is 101.325 kpa. Find the humidity ratio of moist air on this day. (e) What is secondary refrigerant? Where is it used? (f) What is the function of Thermo-electric Refrigeration? 2.In an A/C system air at a flow rate of 2 kg/s enters the cooling coil at 25 0 c & 50% RH & leaves the cooling coil at 11c & 90% RH. The apparatus dew point the cooling coil is 7 0 c.Find (a) The required cooling capacity of the coil (b) SHF for the process © By-pass factor of the cooling coil Assume the barometric pr. To be 1 atm..Assume the condensate water to leave the coil at ADP(h W =29.26 kj/kg) 3.A cooling tower is used for cooling the condenser water of a refrigeration system having a heat rejection rate of 100 kw .In the cooling tower air enters at 35 0 c(DBT) & 24 0 c(WBT) & leaves the cooling tower at a DBT of 26 0 c RH of 95%.What is the required flow rate of air at the inlet to the cooling tower in m 3 /s. What is the amount of make-up water to be supplied? The temp. of make-up water is at 30 0 c,at which its enthalpy (hw) may be taken as 125.4 kj/kg. Assume barometric pr. To be 1 atm. 4.(a) Show the following process on the skeleton psychometric chart: (a)Sensible heating (b)Evaporative cooling (c)Adiabatic chemical dehumidification (d)Cooling & humidification (e)Mixing of Air (b) Derive the expression for enthalpy of moist air & dry air.
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GANDHI INSTITUTE OF TECHNOLOGICAL ADVANCEMENT2 nd INTERNAL EXAMINATION (Additional)
Sub:Refrigeration & Air Conditioning F.M.:20Sem:7th semesterBranch:Mechanical Engg.
(Answer all the question of Q. No. 1 & any two from the rest of the question)
1. (a)Write any five physical & chemical properties of Refrigerants ? (b)Why freons expected to be phase out as refrigerants? Which are. Eco-friendly replacement refrigerant being tried? (c)Define room sensible heat factor. How room sensible heat factor line is drawn on psychometric chart? (d)On a particular day the weather forecast states that the DBT is 37 0C,while the RH-50% & the barometric pressure is 101.325 kpa. Find the humidity ratio of moist air on this day. (e) What is secondary refrigerant? Where is it used? (f) What is the function of Thermo-electric Refrigeration?
2.In an A/C system air at a flow rate of 2 kg/s enters the cooling coil at 25 0c & 50% RH & leaves the cooling coil at 11c & 90% RH. The apparatus dew point the cooling coil is 7 0c.Find (a) The required cooling capacity of the coil (b) SHF for the process © By-pass factor of the cooling coilAssume the barometric pr. To be 1 atm..Assume the condensate water to leave the coil at ADP(hW=29.26 kj/kg) 3.A cooling tower is used for cooling the condenser water of a refrigeration system having a heat rejection rate of 100 kw .In the cooling tower air enters at 35 0c(DBT) & 24 0c(WBT) & leaves the cooling tower at a DBT of 26 0c RH of 95%.What is the required flow rate of air at the inlet to the cooling tower in m3/s. What is the amount of make-up water to be supplied? The temp. of make-up water is at 30 0c,at which its enthalpy (hw) may be taken as 125.4 kj/kg. Assume barometric pr. To be 1 atm.
4.(a) Show the following process on the skeleton psychometric chart: (a)Sensible heating (b)Evaporative cooling (c)Adiabatic chemical dehumidification (d)Cooling & humidification (e)Mixing of Air (b) Derive the expression for enthalpy of moist air & dry air.
