# Test: RAC Level - 1

## 25 Questions MCQ Test Mechanical Engineering SSC JE (Technical) | Test: RAC Level - 1

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Attempt Test: RAC Level - 1 | 25 questions in 50 minutes | Mock test for Mechanical Engineering preparation | Free important questions MCQ to study Mechanical Engineering SSC JE (Technical) for Mechanical Engineering Exam | Download free PDF with solutions
QUESTION: 1

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QUESTION: 2

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QUESTION: 3

### One tonnes of refrigeration is equal to

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QUESTION: 4

Thermoelectric refrigeration system is based on

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QUESTION: 5

A heat pump operating based on a reversed carnot cycle between temperature T1 and T2, where T1 is higher absolute temperature and T2 is lower absolute temperature then the COP of heat pump is

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QUESTION: 6

A refrigerator operating based on reversed carnot cycle between T1 and T2 where T1 is high temperature and T2 is lower temperature then COP of refrigerator is

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QUESTION: 7

Horse power and kW required per tonne of refrigeration is expressed as

Solution:

Horse power per ton = 4.75?COP

kW/ton = 3.516/COP

QUESTION: 8

The COP of a heat pump can be increased either by decreasing TH by ΔT or by increasing TL by ΔT. The new COP of the heat pump is

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QUESTION: 9

The COP of a Carnot refrigeration cycle decreases on

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QUESTION: 10

The coefficient of performance of a domestic refrigerator is __________ as compared to a domestic air-conditioner.

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QUESTION: 11

Which one of the following sequence is correct in vapour compression cycle

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QUESTION: 12

In a vapour-compression refrigeration cycle, if  h1 and h2 denote the enthalpies at inlet and exit of the compressor respectively, h3 is the enthalpy at the exit of the condenser and h4 is the enthalpy at the inlet of the evaporator, the COP for the cycle is

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QUESTION: 13

In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the

Solution:

In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the Expansion valve to the evaporator

QUESTION: 14

Formation of frost on evaporator of refrigerator

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QUESTION: 15

In a vapour compression cycle, the refrigerant immediately after expansion valve is

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QUESTION: 16

Sub-cooling in a refrigeration cycle have effect of

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QUESTION: 17

Superheating in refrigeration cycle

Solution:

Explanation : Useful superheating increases both the refrigeration effect as well as the work of compression. Hence the COP (ratio of refrigeration effect and work of compression) may or may not increase with superheat, depending mainly upon the nature of the working fluid. Even though useful superheating may or may not increase the COP of the system, a minimum amount of superheat is desirable as it prevents the entry of liquid droplets into the compressor

QUESTION: 18

Solid CO2 is produced by

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QUESTION: 19

The thermodynamic cycle used in aircraft refrigeration is

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QUESTION: 20

In aircraft, air refrigeration cycle is used because of

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QUESTION: 21

Bell Coleman cycle consists of

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QUESTION: 22

In electrolux refrigerator.

Solution:

Explanation : In Electrolux refrigerator Ammonia evaporates in hydrogen.

The ammonia liquid leaving the condenser enters the evaporator and evaporates into the hydrogen at the low temperature corresponding to its low partial pressure. The mixture of ammonia and hydrogen passes to the absorber into which is also admitted water from the separator. The water absorbs the ammonia and the hydrogen returns to the evaporator. In the absorber the ammonia therefore passes from the ammonia circuit into water circuit as ammonia in water solution. This strong solution passes to the generator where it is heated and the vapor given off rises to the separator. The water with the vapor is separated out and a weak solution of ammonia is passed back to the absorber, thus completing the water circuit. The ammonia vapor rises from the separator to the condenser where it is condensed and then returned to the evaporator.

QUESTION: 23

Which of the following cycles uses air as the refrigerant

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QUESTION: 24

An important characteristic of absorption system of refrigeration is

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QUESTION: 25

The relative coefficient of performance is

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