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Abstract

This investigation into the effect of piston diametral clearance on the performance of a small refrigeration compressor was made to determine the limiting conditions for satisfactory performance.

Six pistons of standard ringless design were used in the same compressor giving clearances ranging from 00004 to 00041 in. The tests were carried out on a refrigerator with a calorimeter-type evaporator using dichlorodifluoromethane.

Particular attention was given to the effects on volumetric efficiency and specific power consumption. These quantities were plotted against pressure ratio over a wide range of operating conditions and an analysis of the losses involved was made and related to the diametral clearance.

Both volumetric efficiency and specific power were found to vary greatly with the clearance, the former being greatest with the minimum clearance but the latter showing a tendency under some conditions to a minimum value for a diametral clearance of 0.0022 in. Honed cylinders and ground pistons are considered essential for good performance.

It is suggested that in addition to piston leakage, entry heating plays an important part in the reduction of volumetric efficiency.

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References

Maclaren

J. F. T.

1953–54 Inst. Refrigeration Paper, ‘Performance of Small Compressors and Valve Behaviour’.

Lorentzen

1952 March, Refrig. Engng, p. 272, ‘Influence of Speed on Volumetric Efficiency’.

A.S.R.E. Data Book

1957–58 ‘Design Volume’, Chapters 4, 18 (American Society of Refrigerating Engineers).

Nagaoka

Hotani

1955 Proc. 9th Int. Congr. Refrigeration, vol. 1, p. 3091, ‘Experimental Researches on the Characteristics of the Compressor Valve’.

Gosney

W. B.

1952–53 Inst. Refrigeration Paper, ‘Factors Affecting the Performance of Small Reciprocating Compressors’.

Smith

E. C.

1935 Proc. Instn mech. Engrs, Lond., vol. 129, p. 477, ‘Determination of Mass Flow in the Vapour Compression Refrigerator’.

Giffen

Newley

E. F.

1940 Proc. Instn mech. Engrs, Lond., vol. 143, p. 227, ‘Refrigerator Performance: An Investigation into Volumetric Efficiency’.

Lorentzen

1955 Proc. 9th Int. Congr. Refrigeration, p. 3, ‘Performance of Automatic Compressor Valves’.

Brown

1951 General Discussion on Heat Transfer, Proc. Instn mech. Engrs, Lond., p. 55, ‘Cyclical Heat Interchanges Between Charge and Cylinder in a Refrigerating Compressor Operating on Freon 12’.

10.

Maclaren

J. F. T.

1955 Thesis, Glasgow University, ‘Automatic Valves in Small High Speed Gas Compressors and Water Pumps’.

11.

Pearson

S. F.

1958 Thesis, Glasgow University and Engineering, vol. 186, p. 485, ‘Component Losses in Refrigeration Compressors’.

Effect of Piston/Bore Clearance in Small Refrigeration Compressors

Abstract

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References