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An aftercooler is used to cool the air coming out from the compressor before it enters the receiver. The air coming out from the compressor at pressure p3 is sufficiently hot at temperature T4 (Fig. 12.15). If this air is cooled in the aftercooler, then the pressure will remain p3, but the temperature will fall from T4 to T4′′. Therefore, the volume of…

Single-stage compression suffers from many disadvantages such as (i) handling of very high pressure range in one cylinder resulting in leakage past the piston, (ii) ineffective cooling of the gas, and (iii) necessitating robust construction of the cylinder to withstand the high delivery pressure. The volumetric efficiency of a single-stage compressor with fixed clearance decreases…

The volumetric efficiency of a compressor can be lowered by any of the following conditions: Figure 12.9 shows the variation in volumetric efficiency with clearance ratio (c), and the pressure ratio (p2/p1), and polytropic index of compression (n) (by changing one factor keeping the other two factors constant). The volumetric efficiency decreases with increase in both…

The volumetric efficiency of a reciprocating compressor is defined as the ratio of the actual free air delivered to the swept volume of the compressor. The free air delivered is (V1–V4), whereas the swept volume is (V1–Vc). Thus, Let  clearance ratio When referred to ambient conditions,

1 Required Work Without Clearance Consider the theoretical p−V diagram for a single-stage air compressor as shown in Fig. 12.7. The work done on air per cycle is represented by the area 1–2–3–4–1. Figure 12.7 p-V diagram without clearance W = area (a − b − 2 − 3 − a) + area (b − c − 1 − 2 − b) − area (a − c − 1 −…

The theoretical p−V diagram for single acting compressor is shown in Fig.12.4. The line 4–1 represents the suction stroke. The air is then compressed adiabatically as shown by the curve 1–2 in Fig. 12.4. It is then forced out of the cylinder at constant pressure p2, as shown by the line 2–3. The work done is represented by the area…

The schematic arrangement of a single-stage reciprocating compressor is shown in Fig. 12.3. It consists of a cylinder with cooling jacket, piston, connecting rod, crank, suction valve, and delivery valve. The piston will be making to-and-fro motions through the crankshaft arrangement and generally run by an electric motor, diesel engine, petrol engine, or steam engine. During…

The several uses of compressed air are as follows:

Compressors are mechanical devices used for increasing the pressure of a gas. Compressors used for producing high pressure air are called air compressors. Air is drawn from the atmosphere by suction process, which is then compressed to the required pressure and delivered to the receiver. Air compressors may be classified as shown in Fig. 12.1. Figure…