NODIA AND COMPANY. Model Test Paper - I GATE Refrigeration and Air Conditioning. Copyright By Publishers

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1 No part of thi publication may be reproduced or ditributed in any form or any mean, electronic, mechanical, photocopying, or otherwie without the prior permiion of the author. Model Tet Paper - I GATE Copyright By Publiher Information contained in thi book ha been obtained by author, from ource believe to be reliable. However, neither Nodia nor it author guarantee the accuracy or completene of any information herein, and Nodia nor it author hall be reponible for any error, omiion, or damage ariing out of ue of thi information. Thi book i publihed with the undertanding that Nodia and it author are upplying information but are not attempting to render engineering or other profeional ervice. NODIA AND COMPANY B-8, Dhanhree Tower It, Central Spine, Vidyadhar Nagar, Jaipur 0209 Ph : enquiry@nodia.co.in Printed by Nodia and Company, Jaipur

2 Q. 1 - Q. 5 carry one mark each. Q.1 Nine cane of water i cooled from 25c C to c Cin 12 hour by a thermoelectric refrigerator. The refrigerator i powered by a 12 Volt car battery that draw amp. of current when running and the refrigerator reemble a mall ice chet. If each the cane ha a volume of 0.50 L, the average COP of thi refrigerator will be (Take: r = 1 / L and c p = 4.18 kj/ - cc) (A) (B) (C) 0.5 (D) 0.22 Q.2 Moit air i paed through a cooling ection where it i cooled and dehumidified. How will be the pecific humidity and the relative humidity of air change during thi proce? (A) Specific humidity will decreae but relative humidity will increae. (B) Specific humidity will increae but relative humidity will decreae. (C) Both pecific humidity and relative humidity will decreae. (D) Both pecific humidity and relative humidity will increae. Q. How will the humidity ratio and the relative humidity of the air contained in a wellealed room change a it i heated? (A) Humidity ratio will increae but relative humidity will remain contant. (B) Humidity ratio will remain contant but relative humidity will increae. (C) Humidity ratio will remain contant but relative humidity will decreae. (D) Humidity ratio will decreae but relative humidity will remain contant. Q.4 Conider a tank which contain 21 of dry air and 0. of water vapor at 0c C and 100 kpa total preure. If the aturation preure of water at 0c C i kpa, the relative humidity and the volume of the tank will be (A) 44.7%, m (B) 66.2%, 2. 4 m (C) 52.9%, 18.7 m (D) 58.2%, m

3 Q.5 A room contain air at 20c C and 98 kpa at a relative humidity of 85 percent. If the aturation preure at 20c C i 2.92 kpa and h = kj/, what will be the partial preure of dry air and the enthalpy per unit ma of dry air? (A) kpa, 52.8 kj/ (B) kpa, kj/ (C) kpa, kj/ (D) kpa, kj/ Q. 6 - Q. 15 carry two mark each. Q.6 In the figure hown, the two airtream are mixed teadily and adiabatically. The firt tream enter at 2c C and 40 percent relative humidity at a rate of 20 m / min, while the econd tream enter at 12c C and 90 percent relative humidity at a rate of 25 m / min. If the mixing proce occur at a preure of 1atm, the pecific humidity and the enthalpy of the mixture are (A) , 68 kj/ (B) , 45 kj/ (C) , 54 kj/ (D) , 2 kj/ Q.7 Conider a ga refrigeration cycle with a preure ratio of which ue helium a the working fluid. At the compreor inlet the temperature of helium i - 10cC and at the turbine inlet i 50c C. The ientropic efficiencie for both the turbine and the compreor are of 80 percent. For a refrigeration rate of 18 kw, the coefficient of performance and the ma flow rate of the helium, repectively, are (Take c p = kj/ -K and k = ) (A) 0.56, / (B) 0.46, / (C) 0.540, / (D) 0.250, /

4 Q.8 An ideal ga refrigeration ytem with two tage of compreion with intercooling i hown in figure. Air entering the firt compreor at 90 kpa and - 18cC. Each compreion tage ha a preure ratio of 4 and the two intercooler can cool the air to 10c C. The ientropic efficiencie of each compreor and turbine are 85% and 95%, repectively. Thi ytem erve a kj/ h cooling load. Auming contant pecific heat at room temperature, what will be the coefficient of performance of thi ytem and the rate of air circulation through thi ytem? (Ue: = kj/ K and k = 14. ) c pair, - (A) 0.415, / (B) 0.742, / (C) 0.890, / (D) 0.59, / Q.9 In an air duct, a flow of moit air at 45c C with a flow rate of 0.2 / dry air i mixed with a flow of moit air at 25c C and 0. / of dry air. The abolute humiditie at 45c C and 25c C are and 0.018, repectively. Alo the enthalpie at the given temperature are 79 kj/ dry air and 90.5 kj/ dry air, repectively. If there i no ignificant heat tranfer in the duct and after the mixing there i heat tranfer to a final enthalpy of 94 kj/ dry air, what will be the enthalpy before mixing and the heat tranfer in thi proce? (A) kj/, 520. kw (B) kj/,.04kw (C) kj/, 226. kw (D) 85.9 kj/, 4.05 kw

5 Q.10 A wet cooling tower hown in figure, i to cool 60 / of water from 40c C to 26cC. Atmopheric air enter the tower at 1atm with dry and wet-bulb temperature of 22c C and 16c C, repectively. If the air leave at 4c C with a relative humidity of 90 percent, the volume flow rate of air into the cooling tower and the ma flow rate of the required makeup water will be (A). 6 m /, 087. / (B) 5. 8 m /, / (C) m /, / (D) 44.9 m /, 1.16 / Q.11 In the figure hown, the two airtream are mixed teadily and adiabatically. The firt tream enter at 2c C and 40 percent relative humidity at a rate of 20 m / min, while the econd tream enter at 12c C and 90 percent relative humidity at a rate of 25 m / min. If the mixing proce occur at a preure of 1atm, the pecific humidity and the enthalpy of the mixture are

6 (A) , 68 kj/ (B) , 45 kj/ (C) , 54 kj/ (D) , 2 kj/ Numerical Anwer Quetion Q.12 The figure how an ideal ga refrigeration ytem with three tage of compreion with intercooling. Air enter the firt compreor at 80 kpa, - 20cC and each compreor in thi ytem ha a preure ratio of 5. The air temperature at the outlet of all intercooler i 15c C. Uing contant pecific heat at room temperature, what will be the COP of thi ytem? (Take: c p = kj/ -K and k = 14. ) Q.1 A room i filled with aturated moit air at 25c C and a total preure of 100 kpa. The aturated preure at 25c C i.1698 kpa. If the ma of dry air in the room i 100, what i the ma of water vapor (in )? Common Data Quetion Common Data for Quetion 14 and 15: In a Carnot vapor refrigeration cycle refrigerant R- 14a i ued a the working fluid. The refrigerant enter the condener a aturated vapor at 28c C and leave a aturated liquid. The evaporator operate at a temperature of - 10cC. The thermodynamic propertie of R-14 i given in table.

7 Temperature ( c C) Preure (kpa) Enthalpy (kj/) Entropy (kj/-k) h f h g f g Q.14 What will be the work input to the compreor and the work developed by the turbine in kj/ of refrigerant flow, repectively? (A) 25.98,.86 (B) 19.50, 2.90 (C) 8.56, 5.79 (D) 2.46, 4.6 Q.15 What will be the heat tranfer to the refrigerant paing through the evaporator and the coefficient of performance of the cycle? (A) kj/, 4.8 (B) kj/, 8.0 (C) kj/, 6.91 (D) kj/, 10.6 END OF THE QUESTION PAPER For detailed Solution of thi tet paper pleae mail to enquiry@nodia.co.in. Pleae mention your Name, College, Graduating Year and GATE Regitration Number in the mail.