Dynamic Simulation of Household Refrigerators: Numerical Model and Experimental Comparison

This work presents a dynamic model to simulate a whole household refrigeration unit taking into account both the refrigeration cycle itself and the refrigerated compartments network. The methodology implemented to achieve the transient simulation of the whole system combines a steady-state approach for the refrigerating cycle loop with a transient approach for the refrigerated compartments loop. Both loops are solved at each time step (the linking boundary conditions for the refrigerating cycle and the compartments network are the air temperature of the evaporator chamber and the heat generated by the evaporator, respectively). The numerical infrastructure implemented to simulate the whole system and its elements is described in [1]. On one hand, the refrigerating cycle loop includes appropriate numerical models for the main components, namely, hermetic compressor, wire-and-tube condenser, non-adiabatic capillary tube [2], and finned-tube evaporator. In addition, the receiver located at the outlet position of the evaporator, is also considered and modeled according to [3]. On the other, the refrigerated compartments loop is made up of connected chambers and a damper to regulate the cold air flow going to the refrigerator and freezer. The transient solution of the system includes two important features: i) a numerical model for the refrigerating cycle when the compressor is turned off, and ii) a control system to regulate the compartments temperatures by means of the damper position and the compressor working condition. In the first part of this work the main details of the resolution procedure and the numerical model of both the whole system and all its components are given. In the second part a set of parametric studies to analyse the influence of specific aspects of the main elements on the refrigerating cycle is carried out, namely, arrangements of fins and tubes in the evaporator, non-adiabatic capillary tube geometrical configurations, and gap between wire-and-tube condenser and rear wall. The trends of the numerical results are compared against experimental data at similar conditions. In the last section, an illustrative numerical case including most of the model features is shown in order to see the model potential. REFERENCES [1] N. Ablanque, C. Oliet, J. Rigola, O. Lehmkuhl, C.D. Pérez-Segarra,“Modular Simulation of Vapour Compression Systems with an Object-Oriented Tool”, International Refrigeration and Air Conditioning Conference at Purdue, 2377, Purdue, IN, USA, 2012. [2] N. Ablanque, J. Rigola, C.D. Pérez-Segarra, A. Oliva, “Numerical simulation of capillary tubes. Application to domestic refrigeration with isobutane”, International Refrigeration and Air Conditioning Conference at Purdue, 2377, Purdue, IN, USA, 2010. [3] A. Sadurni, Numerical Analysis and Experimental Studies on Vapour Compression Refrigerating Systems. Special Emphasis on Different Cycle Configurations. PhD Thesis. Universitat Politècnica de Catalunya, Terrassa, Spain, 2012.