A Study on a Numerical Modelling of Discharge Line Flow Analysis of a Household Type Refrigerator

The main component that determines the performance and efficiency of the refrigeration system is the compressor, which is the major energy consumer in a vapor-compression refrigeration system. In hermetic compressors for household refrigerators, one of the major factors that influences the total compressor efficiency is the flow efficiency of discharge line. In order to find out the effect of the structural changes to flow losses and pressure fluctuations at discharge line, this paper presents a three-dimensional CFD model and experimental study of a hermetic reciprocating compressor. In the first phase of this study, transient numerical flow analysis was developed and it was determined whether or not it overlaps with the experimental measurements. The CFD model results were compared with the experimentally obtained pV indicator diagram and transient pressure measurements of discharge plenum by varying the rotation speed of the modelled inverter hermetic reciprocating compressor. The result of the studies helps to identify the effect of the discharge line design parameters to the system performance

Investigation of Flow Losses Through Discharge Line of Household Type Refrigerator Compressors

Nowadays, increasing the efficiency of white goods and small house appliances has become necessity as a result of the technological developments, competition and energy policies. As a basic component of the cooling system, compressor is the most fundamental element for determining the performance and efficiency of the system. In hermetic compressors for household refrigerators, one of the major factors of total compressor efficiency is the discharge line flow efficiency. In this paper, the effects of some of the structural changes to flow losses at discharge line of a hermetic reciprocating compressor were investigated experimentally. For this study, 3 different conceptual designs were created based on the discharge line design parameters such as line diameter, resonator volumes and line length. By performing precise pressure measurements and calorimeter tests, performance and pressure drop rates of conceptual designs were compared against the base model and each other of the conceptual design compressors. The result of the experimental studies helps to identify the effect of the discharge line design parameters to the system performance

Comprehensive Study of Compact Heat Exchangers with Offset Strip Fin

This chapter is aimed to address the performance of compact heat exchangers with offset strip fin, which have been studied by the researchers in detail for decades. The history and basic features of offset strip fins (OSF) are described first to introduce the fin geometry. Then, the effect of the fin geometry on the performance of the offset strip fin is given from experimental and numerical aspects, respectively. Flow streams evolution under varying offset strip geometries is summarized in order to demonstrate the physical impact on the flow. The thermohydraulic features of the flow in the offset strip fin are investigated by considering the Colburn j‐factor and friction (f) factors in diverse flow regimes. Furthermore the criteria, flow area goodness factor j/f, the ratio j/f1/3 and thermohydraulic performance factor JF, derived from the mentioned dimensionless factors, are also used as a scale of the performance of the structure and reported in the chapter

Comprehensive Study of Heat Exchangers with Louvered Fins

The purpose of this chapter is to describe the basic physical features and the analysis of the thermal-hydraulic performance of the louver fins. The terminology which is used widely in the field of compact heat exchanger with louvered fin is described. The flow phenomenon affected by the operating conditions and the geometric parameters of the louvered fin is examined using the flow visualization techniques found in the literature. A methodology is given to calculate the heat transfer and the friction factor. Stanton number, Colburn j-factor and friction factor are defined as a performance criteria and the variations of these criteria with respect to the Reynolds number and the geometric parameters of the louvered fin. The combinations of these dimensionless number such as area goodness factor (j/f), volume goodness factor (j/f1/3) and JF number related with the volume goodness factor are discussed in terms of overall performance criteria. Finally, the correlations of the louvered fin heat exchanger and their tabulated data was summarized

Transient exergy analysis of the condenser and evaporator of an air source heat pump water heater

In this study the performance of an air source heat pump water heater is assessed from exergy point of view in component wise. In order to investigate the work potential of energy, the destruction on the exergy is analyzed and results are summarized for the components individually. The exergy destruction of the system is studied by considering real paths of the pressure and temperature data which are collected during the experiments of the ASHPWH under varying environmental conditions. In the following step, the evolution of the exergy destruction of the system is calculated by a code which is compiled on MATLAB along these temperature and pressure paths. The obtained results reveal the importance of the transient exergy analysis by providing detailed information about exergy destruction of the system such as where it drives up and reaches up to its max and where it drops down and evolves on a smooth path.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Analysis of an irreversible Ericsson engine with a realistic regenerator

An internally irreversible Ericsson engine, with a realistic regenerator, has been analyzed. The study considers internal irreversibilities with the introduction of turbine and compressor thermal-efficiencies and pressure-drops present in realistic regenerators. The effects of internal irreversibilities on the power output and thermal efficiency of the cycle have been determined using the finite-time thermodynamics. Maximum power-density, rather than maximum power, was used as the criterion for optimization, with the objective of having a more efficient small-sized engine.

Optimal design of the regenerative gas turbine engine with isothermal heat addition

A regenerative gas turbine engine, with isothermal heat addition, working under the frame of a Brayton cycle has been analyzed. With the purpose of having a more efficient small-sized gas turbine engine, the optimization has been carried out numerically using the maximum power (MP) and maximum power density (MPD) method. The effects of internal irreversibilities have been considered in terms of the isentropic efficiencies of the turbine and compressor and of the regenerator efficiency. The results summarized by figures show that the regenerative gas turbine engine, with isothermal heat addition, designed according to the maximum power density condition gives the best performance and exhibits highest cycle efficiencies.

Heat exchanger design studies for molten salt fast reactor

In this study, conceptual design for primary heat exchanger of the Molten Salt Fast Reactor is made. The design was carried out to remove the produced heat from the reactor developed under the SAMOFAR project. Nominal power of the reactor is 3 GWth and it has 16 heat exchangers. There are several requirements related to the heat exchanger. To sustain the steady-state conditions, heat exchangers have to transfer the heat produced in the core and it has to maintain the temperature drop as much as the temperature rise in the core due to the fission. It should do it as fast as possible. It must also ensure that the fuel temperature does not reach the freezing temperature to avoid solidification. In doing so, the fuel volume in the heat exchanger must not exceed the specified limit. Design studies were carried out taking into account all requirements and final geometric configurations were determined. Plate type heat exchanger was adopted in this study. 3D CFD analyses were performed to investigate the thermal-hydraulic behavior of the system. Analyses were made by ANSYS-Fluent commercial code. Results are in a good agreement with limitations and requirements specified for the reactor designed under the SAMOFAR project