Fluid Flow in the Oil Pumping System of a Hermetic Compressor

Abstract. Development process of reciprocating compressors can be simplified by using simulation tools. Modelling of a compressor requires a trade-off between computational effort and accuracy of desired results. This paper presents experimental validation of the simulation tool, which can be used to predict compressor behaviour under different working conditions. The mathematical model provides fast results with very good accuracy, however the model must be calibrated for a certain type of compressor. Small air compressor was used to validate an in-house simulation tool, which is based on mass and energy conservation in a control volume. The simulation tool calculates pressure and temperature history inside the cylinder, valve characteristics, mass flow and heat losses during the cycle of the compressor. A test bench for the compressor consisted of pressure sensors on both discharge and suction side, temperature sensor on discharge side and flow meter with calorimetric principle sensor.

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“…Overall compressor efficiency was evaluated, comparing power consumption and work done by the compressor, eq. (6).…”

Section: Compressor Efficiencymentioning

confidence: 99%

“…Posch [6] analysed the whole compressor using CFD. Aigner [7] developed his own three dimensional numerical code for compression chamber and suction and discharge line.…”

Section: Introductionmentioning

confidence: 99%

Experimental validation of mathematical model for small air compressor

et al. 2017

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“…The oil mass flow rate at steady-state operating conditions is determined by experiments [7]. Applying a first order upwind scheme for the calculation of the outlet enthalpy flow, the energy balance of the considered control volume yields the following equations for the oil temperatures: …”

Section: Lumped Control Volumesmentioning

confidence: 99%

Numerical Analysis of the Thermal Behavior of a Hermetic Reciprocating Compressor

Posch¹,

Hopfgartner²,

Berger³

et al. 2017

JEASE

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A numerical model to predict the temperature field in a hermetic reciprocating compressor for household refrigeration appliances is presented in this work. The model combines a high resolution three-dimensional heat conduction formulation of the compressor's solid parts, a three-dimensional CFD (computational fluid dynamics) approach for the gas line domain and lumped formulations of the shell gas and the lubrication oil. Heat transfer coefficients are determined by applying CFD to the gas line side and correlations from the literature on the shell gas and oil side, respectively. The valve in the gas line simulation is modelled as a parallel moving flat plate. By means of an iterative loop the temperature field of the solid parts acts as boundary condition for the CFD calculation of the gas line which returns a cycle averaged quantity of heat to the solid parts. Using an iteration method which is based on the temperature deviation between two iteration steps, the total number of iterations and consequently the computational time can be reduced. The loop is continued until a steady-state temperature field is obtained. Calculated temperatures of the solid parts are verified by temperature measurements of a calorimeter test bench.

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