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Q1— Section header —
1.1Various options are given as possible answers to the following questions. Choose the answer and write only the letter (A D\ next to the question number (1.1.1
1.1.10\in the ANSWER BOOK.
1.1.1ctual COP/ heoretical COP
1.1.2In the vapo ur compression cycle, the condition of the refrigerant is saturated liquid ..
1.1.3
1.1.4The vapour compression refrigerator employs the following cycle Rankine Carnot
1.1.5The p resence of moisture in heat transfer the
1.1.6Air refrigeration operates on the following cycle Rankine cycle Erickson cycle Reversed Carnot cycle
1.1.7The higher temperature in a vapour compression cycle occurs at the eceiver
1.1.8One of the purposes of sub reduce compressor overheating ensure that only liquid and not the vapour enters the expansion
1.1.9The c ondensing temperature in a refrigerator is temperature of the cooling medium
1.1.10Which ONE of the following is NOT a desirable property of a refrig erant?
1.2FIGURE 1 below shows a p ressure nthalpy ( h\ iagram
Q2— Section header —
Q2— Section header —
2.1.3in the ANSWER BOOK.
2.1.3
2.3State FOUR advantages of using PVC plastic for water piping [20] (11041583\20
Q3— Section header —
3.1Briefly define the following refrigeration terms
3.1.1Sub cooling
3.1Superheating
3.1Volumetric efficiency
3.1
3.2Explain the operation of a current type starting relay. (7\
3.3A six cy linder compressor rotating at 20 revolut ions per second has a bore of 30 mm and a stroke length of 70 mm. It delivers refrigeran
Q4— Section header —
4.1Name FOUR methods that can be used to control capacity in a condenser.
4.2Give TWO advantages and TWO disadvantages of a flooded evaporator. (4
4.3Explain the function of a heat exchanger as well as where it should be installed in a refrigeration system. (6\
4.4State SIX main requirements to be considered in the design and selection of evaporators. (6\ [20]20
Q5— Section header —
5.1Indicate whether the following statements are TRUE or FALSE. Choose the answer and write only 'true' or 'false' next to the question number (5.1.1
5.1.5\ the ANSWER BOOK.
5.1.1 A refrigerant should have high vapour density.
5.1.2 A refrigerant should have high enthalpy of vaporisation.
5.1.3 The thermal conductivity of a refrigerant should be high.
5.1.4A refrigerant should have a low cost.
5.1
5.2The f la shing of gas in liquid lines is a common occurrence that is undesirable in refrigeration.
5.2.1 Define the term flash gas
5.2.2 Name TWO methods tha t are used to prevent the flashing of gas. (2
5.2.3What is the most undesirable effect of the flashing of gas? (1\
5.3FIGURE 4
5.3Figure 4 shows a component commonly used in the refrigeration industry. Answer the following questions pertaining to this common component.
5.3.1Name the component shown in Figure 4. (1\
5.2.2State the purpose of installing this component. (1
5.2.3List FOUR faults occur in the industry that makes the in stallation of the component in Figure 4 important. (4
5.4Give FOUR daily inspections activities done on a reciprocating compressor. (4\ [20] TOTAL: 100 (11041583\20