Green “Perry’s Chemical Engigneers’ Handbook
- D.W.R.H. Perry
- ED. McGRAW-HILL
The paper deals with the thermal expansion of pistons for refrigeration compressors, that were in the past of gray cast iron, but presently are made of sintered steel.. The design must ensure the compatibility of components thermal expansion to obtain correct gap between piston and cylinder, both for performance and reliability reasons. Sintered steel parts have a broad range of porosity distribution, according to the pressure distribution during the powder pressing. The overall elastic and thermal properties of the sintered piston were estimated by combining the properties of each constituent (ferrite, pearlite, void, magnetite). The local constituent volume fraction was measured by quantitative metallographic analysis. To predict steady-state thermal dilatations, the thermo-mechanical modeling was carried out by a simplified coupling between structure and thermal-fluid, using overall heat transfer coefficients estimated at average temperature and velocity conditions.