Name: Neil Chester C.
ME 115-1P: Air Conditioning
Yr. & Sec. 5 / B39
Date September 11, 2020
Hernaez
Laboratory Activity # 3 (Date of Submission: September 11, 2020)
ENGR. JOSE
R.
FRANCISCO,
PME
-
PROFESSOR
-------------------------------------------------------------------------------------------------------------------------------------------INSTRUCTION: Solve the following problems, correctly and systematically, and show all the necessary figures.
--------------------------------------------------------------------------------------------------------------------------------------------
Prob. # 1] Outdoor air is 24 oC DB and 15 oC WB passes through an air washer in which water is
recirculated. The air washer has a humidifying efficiency of 70 %. It is then heated by a heating coil with
a coil surface temperature of 27 oC and a by-pass factor of 0.30. For 50 m3/min of outside air supplied,
determine: a) the capacity of the humidifier in TR; and b) the capacity of the heating coil in kW.
Prob. # 2] A class room of 60 seating capacity is air conditioned. The outdoor air conditions are 32 oC DB
and 22 oC WB and the class room is to be maintained at 22 oC DB and 55 % RH. The quantity of outside
air supplied is 0.50 m3/min per student. The comfort conditions are achieved first by chemical
dehumidifying the air and then cooling by the use of cooling coil. Determine: a) the DB temperature of
the air leaving the chemical dehumidifier; b) the capacity of the dehumidifier; c) the capacity of the
cooling coil is 0.30, determine the mean surface temperature of the cooling coil.
Prob # 3] A space to be air conditioned has a sensible heat load of 36 kW and a latent heat load of 10.2 kW. The
space is to be maintained at 26 C DB and 50 % RH. Outside air is at 32 C DB and 24 C WB temperatures. With a
reheater to satisfy the space conditions, the conditioned air will enter the space at 19 C. If 45 % of the supply air is
fresh air, and the rest is recirculated, find:
a. the volume flow rate of fresh air at supply conditions;
b. the apparatus dew point temperatrure;
c. the refrigeration load in TR; and
d. the reheater capacity.
Prob. # 4] The temperature to be maintained in an office building is 26 C DB and 18 C WB. The sensible heat is
77.6 kW and the latent heat gain is 14.3 kW. The cooling and dehumidifying of the air is accomplished by passing it
through a spray-type washer with water chilled by refrigeration. The air is then heated to 18 C then supplied to the
room. Find:
a. the apparatus dew point temperature of washer;
b. the tons of refrigeration necessary if 60 % of air is recirculated and 40 % is new air at 35 C DB and 29 C
WB.
c. Draw the schematic flow diagram of the air condition system with water cooled condenser.
Prob. # 5] An assembly hall was to have an air conditioning unit installed which would be maintained at 26 C DB
and 50 % RH. The unit delivers air at 15 C DB and the calculated sensible heat load is 150 kW and latent heat load
is 51.3 kW. Twenty percent by weight of extracted air is made up is made up of outside air at 34 C DB and 60 % RH
while eighty percent is extracted by the air conditioner from the assembly hall. Determine the refrigeration load in
TR and the ventilation load.
BE HONEST
Even if others are not; Even if others will not; Even if others cannot
“He who walks honestly walks securely, but he whose ways are crooked will fare badly.”
Proverb 10:9