Refrigeration and Air- Conditioning is a significant topic from GATE perspective.
Our experts have devised this article so as to help our readers learn on the strategy to prepare for Refrigeration and Air- Conditioning section of GATE 2017.
This article will cast light on the important sub-topics to prepare under Refrigeration and Air-Conditioning section of GATE Mechanical 2017.
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Important Topics from Refrigeration and Air-Conditioning/ What to Prepare for GATE 2017
Air Conditioning || Important topics for GATE 2017
- You must have a general idea of the basic working of Air Conditioning system and the types of Air-Conditioning systems
- You must prepare Psychrometric charts with due emphasis on numerical part.
- You must thoroughly study various Psychrometric processes and Cycles
- You must lay a lot of emphasis on practicing numerical questions under psychrometric processes and psychrometric charts as they are very important from examination perspective
Refrigeration || Important Topics for GATE 2017
- You must have an overview of the basic working of Refrigeration system and various types of refrigerants.
- Study topics like Vapour refrigeration cycle, heat pumps, gas refrigeration and Reverse Brayton cycle in depth as they are really important under this section
- Practice a variety of numericals on various topics listed above as numericals carry a lot of weight age in GATE exam
Solved Questions from Previous GATE Papers
A vapour absorption refrigeration system is a heat pump with three thermal reservoirs as shown in the figure. A refrigeration effect of 100 W is required at
250 K when the heat source available is at 400 K. Heat rejection occurs at 300 K.
The minimum value of heat required (in W) is
( COP)ref = Refrigeration Effect / Work Done = T1/ (T2 - T1 )
100/W = 250/(300-250)
W = 20 watt
For supply this work, heat is taken from reservoir 3 & rejected to sink 2.
Efficiency = W/ Q3 = (T3 – T2)/ T3 (It works at heat engine)
T3 = 400
So , Q3 = 80 Watt
Moist air at a pressure of 100 kPa is compressed to 500 kPa and then cooled to 35 degree C in an aftercooler. The air at the entry to the aftercooler is unsaturated and becomes just saturated at the exit of the after cooler. The saturation pressure ofwater at 35 degree C is 5.628 kPa The partial pressure of water vapour (in kPa) in the moist air entering the compressor is closest to
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