This set of Thermal Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Reciprocating Steam Engine – Theoretical Indicator Diagram”.
1. An indicator diagram shows _____
a) The variation of temperature of the steam and its pressure during the cycle of operations
b) The variations of temperature and volume of steam during the cycle of operation
c) The variations of steam pressure and its volume in the cylinder during the cycle of operations
d) The variation of temperature of steam and its specific volume during the cycle of operations
Explanation: The plot of the variations of steam pressure and volume in the cylinder during the cycle of operations is called an indicator diagram. Indicator diagrams useful in estimating the performance of a reciprocating steam engine.
2. In a theoretical or hypothetical indicator diagram the expansion is assumed to be _____
Explanation: Theoretical or hypothetical indicator diagram is based on some assumptions. One of these assumptions is that the expansion process is hyperbolic.
Mathematically, the following relationship holds true between pressure (P) and volume (V) –
PV = Constant.
3. In the given indicator diagram, Point 1 is called _____
a) Point of cut-off
b) Point of release
c) Point of flow
d) Point of admission
Explanation: At point 1 steam supply is cutoff and hence is called the point of cut-off. The point 5 is called the point of admission and the point 2 is called the point of release. During the process point 5 to point 1 steam is admitted inside the engine cylinder.
4. Which of the following processes is the expansion process? (Refer to the given image)
a) Process 5 to 1
b) Process 1 to 2
c) Process 2 to 3
d) Process 3 to 4
Explanation: Process 1 to 2 represents the expansion process. The process is hyperbolic. During the expansion process the steam expands in the engine cylinder to the end of the stroke. Point 1 and 2 are called point of cut-off and point of release respectively.
5. With reference to the given image, steam is admitted in the engine cylinder at _____
a) Point 5
b) Point 1
c) Point 2
d) Point 3
Explanation: At point 5 steam is admitted in the engine cylinder. The steam admitted has same pressure as the boilers. Point 5 is also called as point of admission. The expansion of steam starts at point 1.
Sanfoundry Global Education & Learning Series – Thermal Engineering
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