MAHATMA GANDHI MISSION’S COLLEGE OF ENGINEERING & TECHNOLOGY A-09, SECTOR-62, GAUTAM BUDHA NAGAR, NOIDA (U.P.) DEPARTMENT OF MECHANICAL ENGINEERING Subject-Refrigeration and Air-Conditioning code –NME-604 Question Bank No.3 TOPICS -UNIT 3 SECTION-A Q1. Each question contain 2 marks .For assignment attempt any Five. a. What is the vapour absorption refrigeration system? b. In an absorption type refrigeration system, heating in generator, refrigeration in evaporator, and cooling by cooling in condenser, take place at 950C,-50C and 300C. Determine the maximum COP of the system. c. What is the refrigerant? d. List the different types of refrigerants. e. List four thermodynamics properties of the refrigerants. f. ,List four safe properties of the refrigerants. g. List four physical properties of the refrigerants. h. What is a secondary refrigerant? i. Give the examples of secondary refrigerants j. List the main components of the vapour absorption refrigeration system. SECTION-B Q2. Each question contain 5 marks .For assignment attempt any Five. a. Discuss the simple absorption refrigeration system with the help of neat sketch. b. Discuss the Practical absorption refrigeration system with the help of neat sketch. c. Deduce the expression used for COP of the absorption refrigeration system. d. In an absorption refrigeration system , the heat is supplied to NH3 generator by condensing steam at 2bar and 90% dry. The temperature to be maintained in the refrigerator is -50C. The temperature of the atmosphere is 300 C. Find the maximum COP possible of the refrigerator. If the refrigeration load is 20 tons and actual COP is 70% of the maximum COP, find the mass of the steam required per hour. e. Discuss the temperature vs concentration diagram for binary mixture. f. Discuss the enthalpy vs concentration diagram. g. Discuss the adiabatic mixing of two stream. h. What is the critical temperature of the refrigerant? Explain its importance in selecting a refrigerant in refrigeration system with example. i. What are the secondary refrigerants? Where it is used? Explain its importance in big ice-manufacturing plants.
j. Explain the Designation system for the refrigerants with examples. SECTION-C Q3. Each question contain 10 marks .For assignment attempt any Two. a. Define primary refrigerant. What are the desirable properties of a primary refrigerant? Give the refrigerant number for the following NH3, CH2F-CF3, and CH3CH2CH2CH3. b. i) Explain in brief, the concept of Adiabatic mixing of two streams, as related to vapour absorption Refrigeration system. Also discuss the significance of Temperature Concentration diagram. ii) Enumerate the classification of Refrigerants. What are the desirable properties of refrigerants? Name some common refrigerants generally used in refrigeration systems. What do you understand by CFC free refrigerants? c. Describe the operation of a Lithium Bromide - Water absorption refrigeration system with the help of a neat labelled diagram. Comment on the possibility of utilizing Solar Energy for the purpose of refrigeration coupled with this system d. With respect to a binary mixture, write short notes on: . (i) Homogeneous and Heterogeneous mixtures (ii) Miscibility (iii) Temperature - Concentration diagram (iv) Enthalpy - Concentration diagram e. What is the function of the following components in an absorption system: i) absorber ii) rectifier iii) analyser iv) heat exchanger v) generator