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Lesson 1: Previous Year Questions on Basics of Refrigeration
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This video covers the question on basic RAC . Previous year questions have very important role to play in ESE preparations and hence this course specifically targets to minimise your effort but maximize your concepts.

Deepali Namdeo
I have done my bachelor's in mechanical engineering from M.I.T.S Gwalior. Currently I am Design Engineer at Cameron, a Schlumberger Company.

U
Unacademy user
यह बहुत ही महत्वपूर्ण जानकारी है जो घर बैठे आपने उपलब्ध करवाई इसके लिए धन्यवाद
  1. RAC PREVIOUS YEAR ESE OBJECTIVES SOLVED ESE MECHANICAL PRESENTED BY: DEEPALI


  2. About ME GATE Qualified. I also have an experience of 11 months teaching Engineering subjects like Industrial, Thermodynamics, SOM, HMT. Currently working as a Design Engineer at "Cameron-A Schlumberger Company" B.tech with honors from M.I.T.S Gwalior. I am pursuing my Post graduate Diploma in Design Engineering for Oil and Gas Industry


  3. CONTENTS RAC PREVIOUS YEAR ESE OBJECTIVES SOLVED ON BASICS OF REFRIGERATION. HEAT ENGINE AND PUMP PREVIOUS YEAR ESE OBJECTIVES SOLVED .PSHYCOMETERY PREVIOUS YEAR ESE OBJECTIVES SOLVED VCRS YEAR ESE OBJECTIVES SOLVED VARS YEAR ESE OBJECTIVES SOLVED


  4. RAC PREVIOUS YEAR ESE OBJECTIVES SOLVED ON BASICS OF REFRIGERATION


  5. 1. One ton refrigeration is equivalent to: IES-1999] (a) 3.5 kW Ans. (a) (b) 50 kJ/s (c) 1000 J/min (d) 1000 kJ/min 2. In a one ton capacity water cooler, water enters at 30 C at the rate of 200 litres per hour. The outlet temperature of water will be (sp. heat of water 4.18 kJ/kg K) (a) 3.5 C [IES-2001; 2003] (b) 6.3 C (c) 23.7 C (d) 15 C Ans. (d) 3.516 x 3600: 4.18 x 200 x (300-x) or x = 14.98 C~ 15 C


  6. 3. In a system: Metabolic rate M, work done by man W, rate of convective, radiative and evaporative heat losses = Q and rate of heat storage-S. Then heat exchange between man and his environment is given byIES-2002] (a) M + W Q+S (b) M-w-q-S Ans. (d) 4. A human body feels comfortable when the heat produced due to metabolism [IES-1999) of human body is equal to the (a) heat dissipated to the surroundings (b) heat stored in human body (c) difference between heat dissipated to the surroundings and heat stored in human body (d) sum of heat dissipated to the surroundings and heat stored in human body Ans. (d)


  7. 5. In conventional refrigerants what is the element responsible for ozone IES-2009] depletion? (a) Chlorine(b) Fluorine (c) Carbon (d) Hydrogen 5. Ans. (a) Ozone Depletion Potential (ODP): According to the Montreal protocol, the ODP of refrigerants should be zero, i.e., they should be non-ozone depleting substances. Refrigerants having non-zero ODP have either already been phased-out (e.g. R 11, R 12) or will be phased-out in near-future(e.g. R22). Since ODP depends mainly on the presence of chlorine or bromine in the molecules, refrigerants having either chlorine (i.e., CFCs and HCFCs) or bromine cannot be used under the new regulations. 6 Which of the following refrigerant has the maximum ozone depletion in the IES-19921 stratosphere? (a) Ammonia (b) Carbon dioxide (c) Sulphur dioxide (d) Fluorine 6. Ans. (d)


  8. Ozone depletion by CFCs occurs by breakdown of: (a)Chlorine atoms from refrigerant by UV radiation and reaction with ozone in troposphere (b)Fluorine atoms from refrigerant by UV radiation and reaction with ozone in troposphere (c)Chlorine atoms from refrigerant by UV radiation and reaction with ozone in stratosphere (d)Fluorine atoms from refrigerant by UV radiation and reaction with ozone in stratosphere 7. [IES-2002] 7. Ans. (c) IES-2008] of Which one of the following is correct? Environmental protection agencies advise against chlorofluorocarbon refrigerants because these react with (a)Water vapour and cause acid rain (b)Plants and cause green house effect (c)Oxygen and cause its depletion (d)Ozone layer and cause its depletion 8. the use 8. Ans. (d)


  9. 9. The reason for a person feeling more comfortable on a warm day if seated in IES-1999] front of an electric fan is that the (a) metabolic heat production is reduced (b) body loses more heat by convection and evaporation (c) body loses more heat by radiation (d) body loses more heat by evaporation and radiation 9Ans. (b) On a summer day, a scooter rider feels more comfortable while on the move than while at a stop light because (a) an object in motion captures less solar radiation. (b) air is transparent to radiation and hence it is cooler than the body (c) more heat is lost by convection and radiation while in motion (d) Air has a low specific heat and hence it is cooler. 10. IES-1998] 10Ans. (c)


  10. 11.The desirable air velocity in the occupied zone for comfort for summer air- [IES-2000] 8Ans. (a) The recommended comfort conditions for different seasons and clothing suitable Top range for 90% conditioners is in the range of (a) 6-7 m/minute (b) 4 5 m/minute (c) 2-3 m/minute (d) 0.5 1.5 m/minute at 50% RNH, air velocity of 0.15 m /s and an activity level of Season 1.2 met. Clothing Iel op,opt acceptance Winter Heavy slacks, long sleeve 0.9 clo 22 C 20 to 23.5 0C shirt sweater and Summer Light slacks and short0.5 clo 24.50C sleeve shirt 23 to 260C Minimal (shorts) 0.05 clo 27.0C 26 to 290C 0.15 m/s = 9 m/minute


  11. 13. Which one of the following statements is correct? [IES-2004] In a domestic refrigerator periodic defrosting is required because frosting (a) Causes corrosion of materials (b)Reduces heat extraction (c) Overcools food stuff (d)Partially blocks refrigerant flow Ans. (b) 14. Consider the following statements: [IES-1997] In the thermoelectric refrigeration, the coefficient of performance is a function of: 1. 2.Peltier coefficient 3. 1.Temperature at cold and hot junctions 5.Thermal conductivity of materials. Of these statements: (a) 3, 4 and 5 are correct (c) 1,2, 4 and 5 are correct Electrical conductivity of materials Seebeck coefficient (b) 1,2, 3 and 5 are correct (d) 2, 3, 4 and 5 are correct Ans. (c)


  12. 17.A passive method to keep the house comfortably warm by solar [IES-2005] conditioning in cold climatic condition is to paint the: (a) Eastern wall of the house by black paint on its outer side (b) Eastern wall of the house by back paints on its inner side (c) Southern wall of the house by black paint on its outer side (d) Southern wall of the house by black paint on its inner side Ans. (b) 180n which factor(s), does the heat lost by the human body in the process of IES-2005 radiation depend? (a) Temperature only (c) Temperature and relative humidity (d) Relative humidity and air motion (b) Temperature and air motion Ans. (a)