Which of the following statements does NOT apply to the volumetric ef...
In actual compressors, a small clearance is left between the cylinder head and piston to accommodate the valves and to take care of thermal expansion and machining tolerances.
A large clearance volume results in low volumetric efficiency and hence large cylinder dimensions increase the contact area between the piston and cylinder and so, increases friction and work.
Volumetric efficiency is given by:
Where c = Clearance ratio.
P2/P1=Pressure;ratio
As the clearance ratio increases, the volumetric efficiency of the reciprocating compressor decreases as the pressure ratio increases.
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Which of the following statements does NOT apply to the volumetric ef...
Introduction:
The volumetric efficiency of a reciprocating air compressor is a measure of how effectively the compressor is able to deliver a specific volume of air at a given pressure. It is influenced by several factors, including inlet temperature, pressure ratio, and clearance ratio. In this question, we are asked to identify the statement that does not apply to the volumetric efficiency of a reciprocating air compressor.
Statement Analysis:
Let's analyze each statement to determine its applicability to the volumetric efficiency of a reciprocating air compressor:
a) It decreases with an increase in inlet temperature:
Inlet temperature refers to the temperature of the air entering the compressor. As the inlet temperature increases, the density of the air decreases, resulting in a decrease in volumetric efficiency. This is because the compressor has to work harder to compress a less dense air, leading to reduced efficiency. Therefore, this statement is applicable to the volumetric efficiency of a reciprocating air compressor.
b) It increases with a decrease in pressure ratio:
The pressure ratio is the ratio of the discharge pressure to the suction pressure in the compressor. As the pressure ratio decreases, the volumetric efficiency of the compressor increases. This is because a lower pressure ratio reduces the amount of work required to compress the air, resulting in improved efficiency. Therefore, this statement is applicable to the volumetric efficiency of a reciprocating air compressor.
c) It increases with a decrease in clearance ratio:
The clearance ratio is the ratio of the clearance volume to the displacement volume in the compressor. As the clearance ratio decreases, the volumetric efficiency of the compressor increases. This is because a smaller clearance volume allows for a higher compression ratio, leading to improved efficiency. Therefore, this statement is applicable to the volumetric efficiency of a reciprocating air compressor.
d) It decreases with an increase in clearance to stroke ratio:
The clearance to stroke ratio is the ratio of the clearance volume to the stroke volume in the compressor. As the clearance to stroke ratio increases, the volumetric efficiency of the compressor decreases. This is because a larger clearance volume reduces the compression ratio, resulting in decreased efficiency. Therefore, this statement is applicable to the volumetric efficiency of a reciprocating air compressor.
Conclusion:
Based on the analysis, we can conclude that statement a) "It decreases with an increase in inlet temperature" does not apply to the volumetric efficiency of a reciprocating air compressor.
Which of the following statements does NOT apply to the volumetric ef...
In actual compressors, a small clearance is left between the cylinder head and piston to accommodate the valves and to take care of thermal expansion and machining tolerances.
A large clearance volume results in low volumetric efficiency and hence large cylinder dimensions increase the contact area between the piston and cylinder and so, increases friction and work.
Volumetric efficiency is given by:
Where c = Clearance ratio.
P2/P1=Pressure;ratio
As the clearance ratio increases, the volumetric efficiency of the reciprocating compressor decreases as the pressure ratio increases.