Solved question paper for RAC May-2023 (B-TECH 6th)
Solved Question Paper
Refrigeration and air conditioning May-2023
PTU • B-TECH • Mechanical Engineering • 6th • May-2023
refrigeration and air conditioning previous year question papers on BRpaper are organized for students of Punjab Technical University’s Bachelor of Technology program in the Mechanical Engineering stream, 6th semester. This section makes it easier to browse subject-wise old question papers for refrigeration and air conditioning, so students can review how questions are typically framed in past exams and get a sense of the exam pattern. Many students search for refrigeration and air conditioning previous question papers while preparing for exams, and this page is built to support exactly that kind of subject-wise browsing and revision. BRpaper is not the official website of Punjab Technical University or any institution, and it does not publish official notices or academic updates.
REFRIGERATION AND AIRCONDITIONING
1. Basic Concept Natural and Mechanical refrigeration; Application of Refrigeration; Units of refrigeration and Coefficient of performance; Refrigeration effect, cooling capacity and COP of a refrigerator; heating effect, heating capacity and COP as heat pump; Reversed Carnot cycle and its limitations
2. Bell Coleman Cycle and Aircraft Refrigeration Bell Coleman Cycle and its analysis; optimum COP and pressure ratio, necessity of air craft refrigeration - air cycle refrigeration systems and their comparison
3. Vapour Compression Refrigeration Cycle Vapour compression cycle on P-V, P-H and T-S diagrams; Deviation of actual cycle from theoretical cycle; Compressor capacity and volumetric efficiency, Analysis of theoretical and actual vapour compression cycles; Effect of suction pressure, discharge pressure, subcooling, super heating and pressure drop in valves on performance and cooling capacity.
4. Vapour Compression Refrigeration with Multiple Evaporators and Compressors Compound compression with single and multiple expansion valves, water intercooling and flash intercooling; multiple load systems with single and multiple expansion valves
5. Vapour Absorption Refrigeration Cycle (No Mathematical Analysis) Principle of absorption system; components of the system; Desirable properties of absorption system refrigerant and absorbent; Aqua - ammonia absorption refrigeration system; Lithium Bromide - water absorption system; Theory of mixtures; temerature concentration and enthalpy concentration diagrams; comparison between absorption and compression systems; Electrolux refrigeration system.
6. Refrigerants Classification and nomenclature of refrigerants; Desirable thermodynamic, chemical and physical properties of refrigerants; comparative study of commonly used refrigerants and their fields of application; Azeotropes; Effect of moisture and oil miscibility; Refrigerants dying agents and antifreeze solution; leak detection and charging of refrigerants; environmental aspects of conventional refrigerants; Ecofriendly refrigerants and action plan to reduce ecological hazards.
7. Non-Conventional Refrigeration Systems (No Mathematical Analysis) Steam Jet Refrigeration; Cascade Refrigeration System; Mixed Refrigeration Systems; Vortex Tube Refrigeration, Thermoelectric cooling; Linde and Claude cycles, cryogenics and its engineering applications.
8. Air Conditioning Concept and Applications; Psychometric properties of air; Dry bulb, wet bulb and dew point temperatures; Relative and specific humidity; degree of saturation adiabatic saturation temperature, enthalpy of air and water vapours; psychometric chart. Human requirement of comforts; effective temperature and comfort charts; Industrial and comfort air conditioning.
9. Psychometric Processes Sensible heating and cooling, cooling with dehumidification; Heating with dehumidification; by-pass factor; chemical dehumidification; adiabatic mixing, air washer.
10. Calculations for Air –conditioning Load and for Rate and state of Supply Air Sources of heat load; sensible and latent heat load; sensible heat factor; appratus dew point temperature; Rate and state of supply - air for air- conditioning of different types of premises.
11. Refrigeration and Air Conditioning Equipment Brief description of compressors, condensers, evaporators and expansion devices; Cooling towers; Ducts; dampers; grills; air filters; fans; room air conditioners; split units; Package and central air conditioning plants.
Solved Questions
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Explain in brief, the concept of thermal analysis of human body, being used for comfort air conditioning. Also give the concept of effective temperature & comfort chart, in brief.Long Answer 10 Marks May-2023 • PTU B-TECH
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Explain the process of leak detection and charging of refrigeration of refrigeration systems.Long Answer 10 Marks May-2023 • PTU B-TECH
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Following data is available for an air conditioning system comprising of filter, cooling coil, fan and distribution system using only fresh air for the purpose of maintaining comfort conditions in summer. RSH = 11.63 K W, RLH = 2.33 K W. Outside design condition: 28°C DBT, 29°C WBT. Inside design condition 21°C DBT, 50% RH. Temperature of air entering the room = 11°C. Calculate RSHF, Coil bypass factor, Rate of flow of air kg/hr, Load on cooling coil, Coil ADP.Long Answer 10 Marks May-2023 • PTU B-TECH
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A Two stage ammonia refrigeration system operates between overall pressure limits of 15 bar and 2 bar respectively. The liquid is sub-cooled to 30°C. The temperature of desuper-heated vapour leaving the water intercooler is also 30°C. The flash chamber separates the dry vapour at 5 bar pressure. The liquid refrigerant then expands to 2 bar, the evaporator pressure. The load on the evaporator is 50 kW. Calculate i) Mass flow rate in different lines; ii) Power.Long Answer 10 Marks May-2023 • PTU B-TECH
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Explain the working principal and construction of Shell and Tube evaporator with the help of a heat sketch.Long Answer 10 Marks May-2023 • PTU B-TECH
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The atmospheric air at 30°C dry bulb temperature and 75 % relative humidity enters a cooling coil at the rate of 200 m3/min. The coil dew point temperature is 14°C and the by-pass factor of the coil is 0.1. Determine: The temperature of air leaving the cooling coil; The capacity of the cooling coil in tonnes of refrigeration; and The sensible heat factor for the process.Long Answer 5 Marks May-2023 • PTU B-TECH
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List the commonly used refrigerants in practice and explain in detail, desirable chemical properties of refrigerants.Long Answer 5 Marks May-2023 • PTU B-TECH
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Draw a neat diagram of lithium bromide water absorption system and explain its working in major field of applications of this system.Long Answer 5 Marks May-2023 • PTU B-TECH
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In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: C.O.P. of the cycle. Also calculate the Carnot C.O.P. and show the percentage difference between the two. Draw the cycle on P-H chart for R-12Long Answer 5 Marks May-2023 • PTU B-TECH
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In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Total heat rejected in the condenserLong Answer 5 Marks May-2023 • PTU B-TECH
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May 2023 In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Power required in the compressor
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May 2023 In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Mass of refrigerant to be circulated
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In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Power required in the compressorLong Answer 5 Marks May-2023 • PTU B-TECH
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May 2023 In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Total heat rejected in the condenser
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May 2023 In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Mass of refrigerant to be circulated
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In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Mass of refrigerant to be circulatedLong Answer 5 Marks May-2023 • PTU B-TECH
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May 2023 In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Total heat rejected in the condenser
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May 2023 In a simple vapour compression refrigeration system using R-12 as refrigerant, the evaporator and condenser temperatures are -10°C and 35°C respectively. If the capacity of the system is 15 tons and the compression is isentropic, calculate the following with the help of P-H chart for R-12: Power required in the compressor
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What is the importance of refrigeration and which are the different methods of producing refrigeration? Also, define the terms and units of refrigeration.Long Answer 5 Marks May-2023 • PTU B-TECH
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Enumerate the factors which affect effective temperature.Very Short Answer 2 Marks May-2023 • PTU B-TECH
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What is the difference between wet bulb temperature and thermodynamic wet bulb temperature?Very Short Answer 2 Marks May-2023 • PTU B-TECH
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What is air conditioning and what is the basic difference between refrigeration and air conditioning?Very Short Answer 2 Marks May-2023 • PTU B-TECH
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What do you understand by hermetically sealed compressors and what are its main advantages over ordinary coupled units?Very Short Answer 2 Marks May-2023 • PTU B-TECH
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Differentiate between Azotropes and Zeotropes.Very Short Answer 2 Marks May-2023 • PTU B-TECH
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Why CFC refrigerants needs to be phased out?Very Short Answer 2 Marks May-2023 • PTU B-TECH
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What do you understand by multistage compression and why it is required in a system when the difference between the evaporator and condenser pressures is large?Very Short Answer 2 Marks May-2023 • PTU B-TECH
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Explain the effect of sub-cooling on COP of vapour compression refrigeration system. Would you desire large sub-cooling and why?Very Short Answer 2 Marks May-2023 • PTU B-TECH
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Define energy performance ratio.Very Short Answer 2 Marks May-2023 • PTU B-TECH
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What do you understand by COP of a refrigeration system?Very Short Answer 2 Marks May-2023 • PTU B-TECH
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Answers about this subject, solved papers, and preparation.
01 Where can I find refrigeration and air conditioning previous year question papers for Bachelor of Technology Mechanical Engineering, 6th semester?
This page lists refrigeration and air conditioning question papers uploaded for Punjab Technical University Bachelor of Technology Mechanical Engineering, 6th semester, organized for subject-wise browsing where available.
02 Are these official Punjab Technical University question papers?
BRpaper is not the official website of Punjab Technical University. These papers are shared for reference and revision purposes only and are not official university material.
03 How can previous year refrigeration and air conditioning papers help in exam preparation?
Reviewing past papers can help you understand how questions are typically framed, notice commonly repeated topics, and get a sense of the exam pattern before your own exam.
04 What kind of topics does refrigeration and air conditioning usually cover?
The question papers here relate to the official refrigeration and air conditioning syllabus set by the university for this course and semester.
05 Does this page include a refrigeration and air conditioning previous question papers or solved answers?
This page focuses on providing access to the previous year question papers themselves. A separate question bank or solved answers may not be available for every paper.
06 Can I find papers for other subjects in the same Bachelor of Technology Mechanical Engineering?
Yes, BRpaper organizes papers by university, course, stream, and semester, so you can browse other subjects within the same Punjab Technical University Bachelor of Technology Mechanical Engineering.