Consider the following statements: Volumetric efficiency of...

Name: Problem 19, Chapter 12: Thermal Engineering
Uploaded: 2021-11-26T20:44:08-08:00
Duration: 1 min 11 s
Channel: Hunza Gilgit
Description: Consider the following statements: Volumetric efficiency of a reciprocating air compressor increases with 1. increase in clearance ratio 2. decrease in delivery pressure 3. multistaging Which of the statements given above is/are correct? (a) Only 1 and 2 (b) Only 2 and 3 (c) Only 3 (d) 1,2 and 3

Consider the following statements: Volumetric efficiency of a reciprocating air compressor increases with 1. increase in clearance ratio 2. decrease in delivery pressure 3. multistaging Which of the statements given above is/are correct? (a) Only 1 and 2 (b) Only 2 and 3 (c) Only 3 (d) 1,2 and 3

Consider the following statements:
Volumetric efficiency of a reciprocating air compressor increases with
1. increase in clearance ratio
2. decrease in delivery pressure
3. multistaging Which of the statements given above is/are correct?
(a) Only 1 and 2
(b) Only 2 and 3
(c) Only 3
(d) 1,2 and 3

Key Concepts

Reciprocating Air Compressor

A reciprocating air compressor operates by converting mechanical energy into the potential energy of compressed air using pistons. Its performance depends on factors such as geometry, pressure ratios, and thermodynamic processes that occur during the compression cycle.

Volumetric Efficiency

Volumetric efficiency is a measure of how effectively a compressor fills its displacement volume with fresh air during the suction cycle. It is influenced by factors like clearance volume, pressure levels, and the design of the compressor, affecting the overall capacity and performance.

Clearance Ratio

The clearance ratio is the ratio of the clearance volume (unused volume that remains in the cylinder at the end of the compression stroke) to the total displacement volume. It directly impacts volumetric efficiency, as a larger clearance volume can lead to increased re-expansion losses during the intake period, reducing the effective intake of fresh air.

Delivery Pressure

Delivery pressure is the outlet pressure at which the compressed air is delivered. Higher delivery pressure typically leads to greater compression work and increases the chances of re-expansion of gases in the clearance volume, which diminishes the amount of fresh air drawn in during the intake stroke, thus negatively affecting volumetric efficiency.

Multistaging

Multistaging involves using two or more compression stages instead of a single stage to compress air stepwise, often with intercooling between each stage. This approach reduces the overall work input for a given final pressure and minimizes temperature effects on volumetric efficiency, thereby enhancing the compressor’s effective performance.

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