Amit Jomde

Bio: Amit Jomde is an academic researcher from Sathyabama University. The author has contributed to research in topics: Linear compressor & Gas compressor. The author has an hindex of 4, co-authored 11 publications receiving 42 citations. Previous affiliations of Amit Jomde include Massachusetts Institute of Technology.

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

Abstract: 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.

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

Abstract: 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...

Review of the current technologies and performances of hydrogen compression for stationary and automotive applications

Abstract: Hydrogen could play an important role as an energy vector in the coming decades in the framework of Sustainable Development. It is the universe's most abundant element and thus a never-ending source of energy. Hydrogen can be directly converted into electric energy by using fuel cells without producing toxic gases. It can also be produced by renewable sources such as biomass, solar and wind energies with no impact for the environment. However, although hydrogen represents a promising eco-friendly solution for energy transition, several issues related to its storage and delivery remain to be solved if it is to be widely used in both stationary and automotive applications. Hydrogen has the lowest volumetric energy density among the commonly used fuels, i.e., 0.01079 MJ/L at atmospheric pressure. Compression is the direct solution to overcome this obstacle. High pressure levels can give satisfying energy densities. The present review summarises the state of the art of the most classical hydrogen compression technologies. We shall present the technical and design features of mechanical compressors, i.e., reciprocating, diaphragm, linear and ionic liquid compressors, as well as of innovative non-mechanical technologies specifically conceived for hydrogen applications, such as cryogenic, metal hydride, electrochemical and adsorption compressors. The basic operating principles and the potential performance levels for each compression technology are analysed. Specifically, their current uses in hydrogen applications and their technological limits are described along with proposals of possible ways of improving their performance levels.

Design of a high thrust density moving magnet linear actuator with magnetic flux bridge

Abstract: This article presents a design of a high thrust density moving magnet linear actuator for linear refrigerator compressor. The shape of permanent magnet (PM) shows great effect on cost, fabrication and magnetic flux density generation in the actuator. Axially magnetised disk shaped PMs are low cost and convenient for fabrication. Moreover, axially magnetised PMs generate high flux density in a specific direction compared to radial magnets. This paper investigates the design of axially magnetised moving magnet linear oscillating actuator (LOA) which operates on single phase alternating supply. Additionally, an alternative path is proposed for the return of magnetic flux from mover to the stator. Using finite element method (FEM) tools, all the parameters of LOA are optimised. Moreover, with the help of a specially designed experimental setup, FEM simulation results are validated. This actuator demonstrates great advancement in thrust force density, motor constant and output power compared to the size of proposed LOA.

Thermodynamic analysis of linear compressor using R1234yf

Abstract: Without crank mechanism, linear compressors can provide significant advantages such as selection of refrigerants, miniaturization, high efficiency, and non-start/stop. Free motion of piston means that displacement can be modulated according to heat load and friction loss of refrigerants. R1234yf is a synthetic refrigerant with global warming potential (GWP) of only 4 which is considered as an ideal replacement for R134a for automobile air conditioner and domestic refrigerator. In this paper, both modelling and measurements were conducted to study the thermodynamic performance of linear compressor using R1234yf in terms of P–V loop, polytropic index, motor efficiency, piston offset, mass flow rate, cooling capacity and coefficient of performance (CoP). The results from the simplified model agree well with measurements. For a pressure ratio of 2.5, a stroke of 12 mm with a condenser temperature of 40 °C, the linear compressor using R1234yf can achieve a motor efficiency of 86%, a cooling capacity of 120 W and a CoP of 3.0. The thermodynamic efficiency of R1234yf is 20–50% lower than R134a. The simplified model is capable of evaluating linear compressor performance with refrigerants.

Scrutinizing the sources of inefficiencies in the piston-cylinder clearance of an oil-free linear compressor.

Abstract: The piston of linear compressors is subjected to low side loads and metal contact can be avoided by feeding high-pressure refrigerant gas from the discharge system into the piston-cylinder clearance. This paper reports a thorough study on the inefficiencies associated with leakage and viscous friction brought about by the transient compressible fluid flow in the piston-cylinder clearance of an oil-free linear compressor. The main objective is to understand the effect of design parameters, such as compressor speed, piston oscillation amplitude, pressure ratio and radial clearance, on the volumetric and isentropic efficiencies. The compressor efficiency was found to be mainly affected by the clearance and pressure ratio. A reduction of 2.5% in the volumetric efficiency and 4.2% in the isentropic efficiency, for instance, were predicted when the radial clearance was varied from 2.5 to 10.0 µm.