The economical value of pressure ratio per stage should be in the range of 3 to 5. K for air, work of compression for unit mass rate of air is Use 5 0. Cooling intake air will increase its density, hence more mass flow rate and for same volume and thus volumetric efficiency increases.
Work done in the compression for different process is plotted on the p-v axis, the compression is flow process therefore the area projected on the vertical axis will be the work interaction. Isothermal process has minimum area projected on the vertical axis, therefore isothermal compression is the most desirable compression process. The expressions V 1 in the work done on the compressor and V 1 — V 4 are nothing but the actual volume entering the compressors.
Work done upon the compressor is same if the volume entering the compressor is same, clearance provided has no effect upon the work input. Consider the following statements in respect of maximum efficiency of a two-stage reciprocating compressor:. W per stage is function of pressure ratio and the inlet temperature T 1 for perfect intercooling the temperature after intercooling in each stage is same,. By perfect inter cooling we will achieve the isothermal compression which required the least work and the efficiency will improve.
Start Learning. Answer Detailed Solution Below Option 1 : two, one, one. Explanation: Compressor The function of a compressor is to take a definite quantity of fluid usually gas and most often air and deliver it to the required pressure. The figure shows the theoretical indicator diagram i. Description - Suction stroke : Inlet valve opens and is air is sucked in the cylinder up to the end of suction stroke. Answer Detailed Solution Below Option 3 : actual compressor work. Explanation: The isentropic efficiency of a compressor is defined as the ratio of the isentropic compressor work to actual compressor work.
Get Started for Free Download App. Simply Supported Plate Poppet Solenoid. Explanation: Plate type or Reed type valves are used in reciprocating compressors. These valves are either floating or clamped, usually, backstops are provided to limit the valve displacement. Spring may be provided for smooth return after opening or closing The piston speed is decided by valve type.
Too high speed will give excessive vapor velocities that will decrease the volumetric efficiency and throttling loss will decrease the compression efficiency.
Plate valves are designed to withstand high pressure and dirty gas applications. Solenoid valve is control units which, when electrically energized or de-energized, either shut off or allow fluid flow.
A Poppet valve is typically used to control the timing and quantity of gas or vapor flow into an engine. Explanation: Compressor: A compressor is a power-consuming device that is used to increase the pressure of gases Clearance volume — It is the volume which is remained in the cylinder even after the piston reaches the top dead center. It is denoted by V c Swept volume — It is the volume swept by the piston in the cylinder or the volume through which the piston travels.
Answer Detailed Solution Below Option 4 : decreases both with increasing clearance ratio and pressure ratio. Concept: Compressor: It is a device used to increase the pressure of a gas. The volumetric efficiency of a compressor is defined as the ratio of actual volume sucked by the compressor at the inlet to the swept volume. P 2 is the delivery pressure and P 1 is suction pressure. So from the formula, it is shown with an increase in clearance ratio and pressure ratio volumetric efficiency is decreased.
Air should be cooled to initial temperature between the stages Pressure ratio for each stage should be same Work done for each stage should be same All of the above. Perfect intercooling means the air should be cooled to initial temperature between the stages.
If there will be no pressure drop occurring in the inter-coolers between stages then the Pressure ratio for each stage becomes the same. Beyond the certain value of pressure, multi-staging is necessary as it helps in saving the construction cost of the material. It also reduces leakage across the piston. Vertical line Horizontal line Parabolic line None of the above. Explanation: Multistage compression: An increase in pressure ratio in single stage reciprocating compressor causes an increase in temperature, a decrease in volumetric efficiency and an increase in work input.
P-V and T-S diagram of the compression with intercooling is shown in the figure below: It can be seen that intercooling is done at constant pressure and is represented by a horizontal line on the P-V diagram. Answer Detailed Solution Below - Answer Detailed Solution Below Option 2 : 8 bar. Concept: In a two-stage compressor, there is intercooling between the suction and delivery pressure at constant pressure by this intercooling some reduction in work supplied to the compressor another advantage of using multi-stage compression is that greater compression can be achieved compared to the single-stage compression.
Answer Detailed Solution Below Option 2 : 9 bar. Determine the theoretical work of the compressor and the heat absorbed by the intercoolers. The air handled is 0. If the compression is isentropic,find: a Piston displacement per cycle 0.
Clearance is 5. A single stage reciprocating air compressor has two double acting cylinders each 46 cm diameter and 36 cm stroke and the piston rods are 50 mm in diameter. An air pollution control device requires 0. When tested under these conditions, performance was within the terms of guarantee.
A 2-stage, double acting air compressor, mm x mm bore x mm stroke, running at RPM, has a free air unloader at each end for capacity control. It is driven by a HP electric motor, volts, 3 phase, 60 Hz, RPM thru superhigh capacity V-belts at sea level installation.
Suction pressure is 1. Safety precautions limit the temperature of the air in the HP cylinder to be 28 C below the flash point of the oil. Assuming perfect intercoooling, what would be the allowable working pressure of this compressor if the compression curve follows PV1.
An industrial plant requires Two steam engine driven three stage air compressor has to compress the under the following conditions: Intercooler pressure between 1st and 2nd stage — KPa Barometer reading — Determine the percent clearance of a single cylinder, double acting air compressor with bore and stroke of 45 cm x 45 cm x RPM.
The compressor is tested and it delivers air from The air is warmed to 38 C during the intake stroke. A two stage, reciprocating air compressor is required to deliver 0. The air enters the HP cylinder at 37 C. The intercooler is water cooled, with the water entering at 22 C and leaving at 32 C.
Take free air conditions to be the same as suction conditions and for perfect intercooling, Calculate: a piston areas for minimum power 0. Find the indicated power of a compressor delivering NH3 at 2. A 2 cylinder, single acting air compressor is directly coupled to an electric motor running at RPM.
A closed metal tank is designed to be safe when subjected to an internal pressure of KPa. The discharge pressure is KPa and there is a 20 KPa pressure drop through the discharge valves. Not counting frictional losses , Find: a the power require to operate the compressor if; 1. An air compressor is direct connected to a heat engine. The compressor handles Determine the percent clearance of a single cylinder, double acting air compressor with bore and stroke of 45 cm x 45 cm by 3 RPS.
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