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Rolling Piston Compressor Operation and Displacement Calculator

Rolling Piston Compressor Operation and Displacement Calculator

Rolling-piston, or fixed-vane, rotary compressors are used in air-conditioning units in capacities up to about 30 kBtu/h and refrigerators up to 2.5 hp. This type of compressor uses a roller mounted on the eccentric of a shaft with a single vane or blade suitably positioned in the nonrotating cylindrical housing, generally called the cylinder block. The blade reciprocates in a slot machined in the cylinder block. This reciprocating motion is caused by the eccentrically moving roller.

Rolling Piston Compressor Section View
Figure 1 - Fixed-Vane, Rolling-Piston Rotary Compressor
(Republished with premission from ASHRAE)

Geometrical displacement for this compressor can be calculated from the following equation:

Vd = π H ( D2 - d2 ) / 4

where

Vd = displacement (in3, mm3),
H = cylinder block height (in, mm),
D = cylinder diameter (in, mm),
d = roller diameter (in, mm)

Typical Rolling-Piston Compressor Performance

Compressor speed 3450 rpm
Refrigerant
R-22
Condensing temperature
130°F
Liquid refrigerant temperature
115°F
Evaporator temperature
45°F
Suction pressure
90.7 psia
Suction gas temperature
65°F
Evaporator capacity
12,000 Btu/h
Energy efficiency ratio
11.0 Btu/W·h
Coefficient of performance
3.22
Input power 1090 W

Related White Papers

Motion Analysis of Rolling Piston in Rotary Compressor (Free Membership required)

Source

  • ASHRAE HVAC Handbook, 2016
  • Motion Analysis of Rolling Piston in Rotary Compressor T. Yanagisawa T. Shimizu I. Chu K. Ishijima Purdue University

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