MIT-World Peace University (MIT-WPU) is a top educational institute located in Pune, India. It is recognized within&nbsp;UGC under Government of Maharashtra Act No. XXXV 2017.&nbsp;

It is part of the MIT group of institutions (established in 1983) which covers 10+ campuses across India and has more than 50,000+ students enrolled across various disciplines at a given point of time. The institute houses 15 schools ranging from Engineering &amp; Technology, Design, Pharmacy, Commerce, Governance among others. It offers undergraduate, postgraduate and PhD programs among different disciplines.&nbsp;

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MIT World Peace University

A microplate heat exchanger is one of the most compact types of heat exchanger used for cooling systems, and not much research was carried out to study the performance of this type of heat exchanger with hybrid nanofluids. In this regard, the performance analysis of the microplate heat exchanger is carried out by estimating the convective heat transfer coefficient in terms of Nusselt number using a hybrid nanofluid. In current research work, Microplate heat exchangers tested using TiO2/ethylene glycol, ZnO/ethylene glycol nanofluids, and a hybrid nanofluid with varied nanoparticle volume fractions. Based on the results, it was found that the thermal conductivity of hybrid nanofluids and the overall heat transfer coefficient by applying hybrid nanofluids show better enhancement than nanofluids. The maximum thermal conductivity ratio between the hybrid nanofluid and the base fluid is 2.10. The maximum Nusselt number of 35.8 was observed for hybrid (TiO2–ZnO/ethylene glycol) at 50 °C and a volume fraction of 4%. © 2023 The Authors

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School of Mechanical Engineering

Engineering and Technology

Case Studies in Thermal Engineering

A case study on analyzing the performance of microplate heat exchanger using nanofluids at different flow rates and temperatures

Aluminium alloys are widely used to manufacture alloy wheels for automobiles. Alloy wheels differ from steel wheels in that they possess high strength to weight ratio, better heat conductivity as well as these wheels have a superior aesthetic look. The present work focusses on the application of corner fatigue test and the simulation of wheel rim in order to reduce its the weight and increase the fatigue life of an aluminium alloy A356 wheel. CATIA V5R19 was used to model the wheel rim, and the fatigue analysis was carried out using Ansys 17. The results of the finite element analysis study indicated that the stress generated in the optimised alloy wheel rim was significantly below the actual yield stress of the aluminium alloy. A mass reduction of 200 gm was achieved through the finite element analysis by proper application of stresses on the wheel rim. The overall weight reduction of 1 kg has contributed to the cost reduction as well as decreased fuel consumption for the automobile. © 2022

Materials Today: Proceedings

Fatigue analysis of alloy wheel using cornering fatigue test and its weight optimization

The experimental parametric investigation on a vapour condenser under vacuum conditions for the vacuum drying application has been presented. The mixture of air-vapour and the non-condensates are extracted from the system using a vacuum condenser. Hence, the vapour's behaviour inside a condenser becomes a subject of study exposed to different operating conditions. In the current study, parameters considered are condenser pressure (20 and 70 mbar), inlet valve orifice diameter (10 and 8 mm), and the cooling water flow rate through the pipes (32 lpm and 16 lpm). The condensation rate increases with the shell pressure and seems to remain unaffected by the chilling water flow rates. The turbulence in the steam flow increases with the increase in the shell pressure. The fluids flowing through tubes at low-velocity experience smaller pressure drops and show low heat transfer coefficients. The reproducibility and repeatability of the tests are excellent. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

International Journal of Ambient Energy

Experimental parametric analysis of vapour condenser for vacuum drying application

A linear compressor is well known for its excellent performance in Stirling cryocooler, space application. Minimum linkages, lesser friction points and lower noise characteristics make the linear compressor more promising in the space application. The same technology has not emerged as an alternative compression technology for ground applications such as home refrigerators, air conditioners, electronic cooling. This paper discusses the challenges observed during the implementation of the moving coil linear compressor in home refrigerators. The prototype moving coil linear compressor has been developed and tested by integrating to the home refrigerator.

International Journal of Ambient Energy, Taylor & Francis

Challenges in implementation of a moving coil linear compressor in a household refrigerator

The opposed piston linear compressor is considered to be the future of silent, reliable and efficient compression technologies. For long valves, less linear compressors have been widely used in cryocoolers for space applications. Recently research has established its high-performance characteristics which are useful in household refrigeration application. Unlike reciprocating compressors which are driven by rotary motors and need a crank connecting rod mechanism to convert rotary into linear motion, a linear compressor is driven by a linear motor which reduces the number of moving parts. This feature makes the compressor more reliable, more efficient and has a silent operation. The piston (suspended on spring stiffness) in the linear compressor is a free piston, i.e. motion of the piston is not constrained hence the performance of the linear compressor is highly dependent on system resonance. Free piston motion offers the unique advantage of ease of modulation, i.e. the stroke of the compressor and hence the delivery mass flow rate coming out of the compressor can be easily controlled by changing the supply voltage. Resonance in the linear compressor is a function of moving mass, spring stiffness and operating or electrical frequency. Achieving resonance in the linear compressor results in maximising the cooling performance of the refrigerator and minimising the input power requirement and hence an increase in the COP of the refrigeration system. The present paper discusses the results from resonance testing of the opposed piston linear compressor for household refrigerator using the fast Fourier transformation analysis. There are different parameters that are considered to optimise the natural frequency of the opposed piston linear compressor, consisting of frequency, moving mass, and spring stiffness. The piston performs compression and suction in a similar manner as in the conventional reciprocating compressor. An opposed piston linear compressor exhibits high energy efficiency due to its simple construction and less moving parts, its mechanical losses are much less than the reciprocating compressor.

Resonance analysis of opposed piston linear compressor for refrigerator application

A prototype of the compressor with moving coil type linear motor has been developed. The developed compressor is integrated with test loop using R134a refrigerant to confirm its performance. The simulation results are validated with the experimental data. The experimental results from the test loop with strokes of 10, 11 and 12 mm for three different pressure ratios of 4, 7, 10 are presented and discussed in this paper. The COP of the system calculated is 1.4 from the test results (for 54 °C condenser temperature and −20 °C evaporator temperature) with the stroke of 10 mm, pressure ratio of 10 and cooling capacity of 134 W. The maximum COP of 2.13 is achieved (for 54 °C condenser temperature and 2 °C evaporator temperature) with the stroke of 12 mm, pressure ratio of 4 and cooling capacity of 325 W. Normal refrigerator compressors utilize lubricant oil but as the refrigerant is changed the oil suitable for particular refrigerant also needs to be changed. The novel linear compressor tested does not utilize lubricant oil. The linear compressor has only one friction point i.e. between the piston and cylinder. The linear compressor utilizes Rulon (low coefficient of friction material) as a special material coated on the piston surface in contact with the cylinder. The oil-free operation of the compressor helps in adapting the refrigerator to different refrigerants without having to consider a change of lubricating oil. Refrigeration system performance with both linear compressor and the conventional reciprocating compressor is measured and compared. System COP with the linear compressor is 18.6% more than with the commercially available reciprocating compressor. The absence of connecting rod and crank mechanism accompanied with oil-free operation due to reduced friction enhance the performance of the linear compressor.

International Journal of Refrigeration, Elsevier

Modelling and measurement of a moving coil oil-free linear compressor performance for refrigeration application using R134a

A mathematical model for a linear compressor with valves is developed. A linear compressor consists of an oscillating motor and a piston rigidly coupled to it. The mathematical model deals with the dynamic equation of a linear compressor consisting of inertia, motor force, and damping. It also solves the electrical circuit equation to estimate the current flowing through the motor circuit. The model considers the dynamic operation of suction and discharge valves. The refrigerant properties are estimated by interfacing the programme with REFPROP to predict the cylinder instantaneous pressure and temperature. Finally, the model predicts the net cooling capacity, compressor input power, and COP for the given compressor geometry. The mathematical model is validated with the experimental results reported by Lee et al. (2004. ‘Linear Compressor for Air-Conditioner.’ L. G. Electronics, international compressor engineering conference, Purdue University, C047, 1–7). Parametric analysis of the compressor is done by varying parameters like input voltage, refrigerant, and superheating temperature of the refrigerant. Results generated by the mathematical model are presented and discussed.

Performance predictions and parametric analysis of valved linear compressor using mathematical model

Linear compressor has emerged as high performance and high efficiency compression technology with its low noise, high efficiency and unique modulation method. The present work reported in this paper is specific to the selection of parameters for flexure bearing used in linear compressor. This paper utilizes FEM as tool to find the equivalent stress and stiffness. In the process of design, selection of optimized parameters is one of the most important steps. The optimized parameters are one which will serve the desired objective like performance and service life at minimum cost. The main objective of this paper is to investigate effect of parameters on flexure bearing to enhance its performance and improve upon the service life of the flexure. Performance of the flexure, service life of the bearing can be enhanced by achieving lower operating stresses and higher stiffness as per the requirement. © 2017 Elsevier Ltd.

Parametric Analysis of Flexure Bearing for Linear Compressor

Pressure-actuated reed valves have to play vital role in compressor of refrigerator. Reed valves are designed considering the pressure gradient and mass flow. The pressure gradient is used to evaluate the valve lift during open condition; the lift and overall component geometry can be used to calculate the mass flow. The performance of this valve influences the compressor efficiency. The valve response (valve flutter) impacts life and reliability of valve in operation. Reed valves are successfully used in reciprocating compressor so that can be used in linear compressor as well that effectively. The parametric study is presented in order to analyze the influence of the valve thickness on valve lifting. The valve model is then simulated using CAE tool. Physical model of valve is also tested. The comparison between simulation result and experiment result of valve model show close agreement. The analysis of reed valve model is carried out with respect to five design points. The model is particularly useful for compressor design. © 2017 Elsevier Ltd.

Modeling and simulation performance of reed valve in linear compressor

The compressor is the most important and expensive component in Refrigeration system. Moreover, linear compressor is an immerging technology in cryogenics and refrigeration field. Hence, it is necessary to improve the reliability of the linear compressor. Failure modes effects and criticality analysis (FMECA) is a step-by-step approach for identifying all possible causes of failures and its effects in designing, manufacturing and assembly process of a product. In this paper, an attempt has been made to perform FMECA of linear compressor. Major failure modes such as valve failure, continuity in coil former, breakage of flexure bearing and leakage are identified. The effect of these identified failure modes is studied. Depending on impact of failure modes on the system components are classified into different levels. In this work, 7 failure modes of linear compressor are prioritized by probability of occurrence, detect ability and severity of the failure, accordingly Risk Priority Number (RPN) is calculated. The results of this analysis can be used to improve the design and optimize the performance of the linear compressor. © 2017 Elsevier Ltd.

Failure modes effects and criticality analysis of the linear compressor

Resonance is a condition under which system vibrates at natural frequency. Resonance produces maximum vibration amplitude. In industry resonance is consider to be harmful for long life of the equipment as amplitude of vibration is very high which results in failure of the component. At the same time there are some equipment’s and applications which work on resonance principal linear compressor is one such application. Under resonance condition it produces maximum amplitude of stroke with minimum input electric power (Exciting force). A linear compressor consists of an oscillating motor and a piston rigidly coupled to it. Oscillations of the linear motor are directly transferred to the piston. The piston is supported by resonant springs to form a free piston system. The use of linear motor reduces the mechanical linkages like crank, connecting rod necessary for converting rotary to linear motion. Hence this machine is compact, operates with very less friction and noise. It is one of the most efficient available compression technologies. The present work discusses model of a linear compressor in CREO. FEM was used to analyze natural frequency of the linear compressor. Various parameters were studied to achieve resonance at 50 Hz condition to meet the Indian power supply conditions.