Maharashtra State Board of Technical Education 2012-6th Sem Diploma Electronics Engineering (DEE) for Electrical Engineering Subject Heating, Ventilation and Air Conditioning(12235) - Quest
MSBTE Sample ques. Paper for Electrical Engineering
Sixth Semester
Subject Heating, Ventilation and Air Conditioning(12235)
Scheme - E
Sample Question Paper
Course Name : Diploma in Electrical Engineering Course Code : EE
Semester : Sixth 12235
Subject Title : Heating, Ventilation and Air Conditioning
Marks : 100 Time: 3 Hour
Instructions:
1. All questions are compulsory.
2. Illustrate your answers with neat sketches wherever necessary.
3. Figures to the right indicate full marks.
4. Assume suitable data if necessary.
5. Preferably, wrrite the answers in sequential order.
Q.l A) Attempt any THREE of the following: 12 Marks
a) Define heat engine, heat pump and refrigerator.
b) Explain why simple NH3 - water absorption refrigeration system cannot be used in practice. What changes does it require to make it practical for use?
c) The latent heat of vapourisation of refrigerant should be high. Justify' it.
d) What is function of a cooling tower? Drawf a neat sketch of Induced type cooling tower.
Q.l B) Attempt any ONE of the following: 06 Marks
a) Compare Unitary A/C system, Packaged A/C & Central A/C system.
b) What are grills & registers and why they are used in air distribution system. What harm will occur if filters are not used in air conditioning system.
Q.2 Attempt any FOUR of the following: 16 Marks
a) What is the function of oil separator? Where is it located? Draw its sketch.
b) Draw a neat sketch of high pressure cut-out and explam its working. Mention its location.
c) What is Sensible Heat Factor (SHF)? Explain the difference between RSHF and GSHF.
d) What is meant by ventilation, what are the types of ventilation? Explain briefly.
e) Analyze the effect of sub cooling and super heating on VCRS.
f) Give comparative analysis of direct expansion and chilled water type central A/C systems.
Q.3 Attempt any FOUR of the following: 16 Marks
a) List out desirable properties of a good primary refrigerant.
b) Analyze the use of rotary and reciprocating compressor with respect to
1. Discharge pressure ii. Mass flow rate iii. Cost
iv. Noise level
c) Define the following psychrometric properties
1. Humidity Ratio ii. Relative humidity
ni. Dew point temperature iv. Wet bulb temperature
d) What are applications of different types of evaporators?
e) What objectives should a insulating material serve?
Q.4 A) Attempt any THREE of the following: 12 Marks
a) Draw a neat sketch of thermostat and explain its working.
b) Explain following sources of heat load.
i. Wall gain load ii. Air change load
c) Draw a neat sketch of constant pressure expansion valve. Briefly explain its working.
d) Explain working of air refrigeration system giving a sketch.
Q.4 B) Attempt any ONE of the following: 06 Marks
a) Draw a neat sketch of VCRS and explain its working.
b) What are advantages & disadvantages of air cooled condenser over water cooled condenser.
Q.5 Attempt any FOUR of the following: 16 Marks
a) An ideal refrigerator works between-10C and -i-350C. If it is allowed to work between -15C and +35C, what effect will be on its performance. Explain.
b) What are desirable properties of a lubricant? What are additives used in lubricants?
c) Explain why secondary refrigerant is used m ice plants.
d) What is saturated air? What is the relation between DBT, WBT and DPT when air is saturated?
e) What are different types of blowers used? Compare them.
f) What is function of solenoid valve? Where is it located in the refrigeration system?
Q.6 Attempt any FOUR of the following: 16 Marks
a) Explain the advantages of microprocessor based controls in refrigeration cycle.
b) What parameters are controlled in air conditioning? Explain where the water comes out from a window A/C.
c) Explain the heating with humidification process & show process on psychenemy chart. What are different types of insulation material used refrigeration and A/C systems?
d) What precautions should be taken while installing transport refrigeration and A/C system?
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