Mohan Lal Dhasan

• Professor (Full) at Anna University, Chennai

The present article examined the thermophysical characteristics of functionalized carbon-based hybrid nanomaterials dispersed in H2O and EG, and studied the optimal combination for cooling electronic chips in a heat sink. Nanomaterials selected were functionalized graphene nanoplatelets (f-GnP) and multiwalled carbon nanotubes (f-MWCNT) mixed in th...

In this work, the performance of HC600a and HFC134a refrigerant-based solar refrigerator with DC compressor was simulated and experimentally compared. Simulation of photovoltaic panel output was done with respect to three parameters: hourly average solar insolation, wind speed, and ambient temperature. This study includes the analysis of different...

A study on the working characteristics of a variable speed DC compressor for variable solar irradiance has been carried out. Two compressors (total cooling capacity of 300 W) were directly connected to the solar photovoltaic (PV) panel, with both having the ability to start when solar irradiance reached 700 W/m2. When individually connected, the mi...

This experimental study analyzed the use of solar photovoltaic energy for operating a novel twin-circuit DC milk chiller without batteries using water-based cold thermal energy storage for different seasons in Chennai, India. HFC-134a and HC-600a were used as refrigerants in the two individual circuits. For each season, the test was conducted conti...

A widely used hydrochlorofluorocarbon (HCFC) refrigerant HCFC‐22 in the split air conditioner (AC) is being phased out in all countries under the Montreal Protocol. Propane (HC‐290) is a favorable substitute for HCFC‐22. The performance, environment impact and cost‐benefit analysis of a split AC unit operated with HCFC‐22 and HC‐290 has been carrie...

A detailed experimental work on the convective heat transfer characteristics of water based hybrid nanofluids with Graphene Nanoplatelets and Multi Walled Carbon Nanotubes in the ratio 1:1 has been performed. Volume concentrations viz., 0.01%, 0.05%, 0.1%, 0.15% and 0.2% were considered. The hybrid nanofluid was passed through the micro channel hea...

This experimental study analyzed the use of solar photovoltaic energy for operating a novel twin-circuit DC milk chiller without batteries using water-based cold thermal energy storage for different seasons in Chennai, India. HFC-134a and HC-600a were used as refrigerants in the two individual circuits. For each season, the test was conducted conti...

Continuous reduction in the size of the electronics for space limitations with higher processing speed generates high heat flux density from the electronics chips during its operational mode. However, this increased heat flux density causes a major problem for the electronics and leads to the failure of the components if not removed properly. This...

This work illustrates the design of a standalone solar power system used to power a milk chiller with 200 W DC compressors using the PVsyst software for different climatic zones in India. The design includes determination of minimum number of PV panels and batteries and also the means of obtaining annual solar fraction values for five different cli...

In view of promoting the utilization of solar photo-voltaic energy for milk chilling application a custom designed milk chiller with DC compressors was fabricated. Two different DC compressors were used operating with HFC-134a and HC-600a refrigerants to ascertain the performance of HFC and HC refrigerants when used in solar powered application. In...

This paper investigates the convective heat transfer characteristics of f-GnP (functionalized Graphene Nanoplatelets) suspended in distilled water. The effect of mass flow rate (5 g/s to 30 g/s) and the GnP concentration (0 vol% to 0.2 vol%) on various heat transport parameters such as convective heat transfer coefficient, temperature drop, Nusselt...

In this work, the performance enhancement of a HFO-1234yf mobile air conditioning (MAC) system with a suction/liquid line heat exchanger (SLHX) was carried out experimentally by tuning the thermostatic (constant superheat) expansion valve (TXV) and its impact on the environment was also evaluated. The optimum charge of HFO-1234yf and HFC-134a syste...

In this work, the experimental investigation on the performance and exergy analysis of mobile air conditioning system with suction line heat exchanger using environmental friendly HFO-1234yf was carried out under varied evaporator air flow rates. The performance was compared with existing HFC-134a results. The performance analysis showed that the c...

In this work, we experimentally investigated the solidification behavior of functionalized graphene-based phase change nanocomposites inside a sphere. The influence of graphene nanoplatelets on thermal transport and rheological characteristics of the such nanocomposites were also discussed. We adopted the covalent functionalization method to prepar...

HC-290 is a promising alternative for HCFC-22, which is an ozone depleting substance under Montreal Protocol. However, HC-290 charge is to be reduced because of its flammability. The objective of this study was to reduce the charge quantity of HC-290 in a split air conditioner , which was originally designed for HCFC-22. The effect of charge reduct...

In this work, the thermal analysis on optimizing the capillary tube lengths of a dual circuit refrigeration system was carried out experimentally. Two refrigeration circuits were individually operated using two DC powered compressors (HFC-134a and HC-600a) instead of conventional AC powered compressors. The capillary tube optimization was done to m...

In the present work, the melting behavior of a fatty acid-based phase change material (PCM) with the addition of functionalized graphene nanoplatelets in a spherical capsule was experimentally studied. The fatty acid-based PCM (OM 08) has been selected for the air-conditioning application with a phase change temperature of 8 °C. The PCM-based nanoc...

The suction line heat exchanger is introduced in a mobile air conditioning system in order to achieve higher energy efficiency. Recent studies reveal that improvement in the system with suction line heat exchanger greatly depends on refrigerant properties and operating conditions. In this work, suction line heat exchanger was incorporated in a mobi...

In the present work, the freezing and melting characteristics of water seeded with chemically functionalized graphene nanoplatelets in a vertical cylindrical capsule were experimentally studied. The volume percentage of functionalized graphene nanoplatelets varied from 0.1% to 0.5% with an interval of 0.1%. The stability of the synthesized samples...

In the current work, the heat transport characteristics of ethylene glycol with different volume fractions of silver nanoparticles dispersed to form a nanofluid that flows through an inner tube of the annular heat exchanger were investigated experimentally. The mass flow rate of nanofluid varied from 5 g/s to 25 g/s at 50°C inlet temperature of nan...

In this work, we report the forced convective heat transfer performance and pressure drop of aqueous ethylene glycol seeded with silver nanoparticles for low temperature applications. Experiments were performed in a tube in tube counter-current heat exchanger using silver nanofluid as the hot fluid under laminar flow conditions. In this study, wate...

In the present work, we report the enhancement in overall heat transfer coefficient of an automobile radiator using graphene nanoplatelets based nanofluid as the coolant. Water-ethylene glycol mixture (70:30 by volume) was used as the base fluid and stable nanofluids were synthesized by non-covalent function-alization method with volume concentrati...

We report the convective heat transfer coefficient and pressure drop of graphene nanoplatelets seeded in water-ethylene glycol mixture flowing through an automobile radiator. The volume concentrations of graphene nanoplatelets were varied from 0.1% to 0.5%. Thermophysical properties such as thermal conductivity, viscosity, density and specific heat...

In the present work, we report the thermal conductivity and specific heat capacity of water–ethylene glycol mixture with graphene nanoplatelets inclusions. Stable nanofluid dispersions were prepared with sodium deoxycholate as the surfactant. Stability of nanofluids was characterized by optical absorption spectroscopy and zeta potential analysis. T...

In this study, we report the effective thermal conductivity and rheological behavior of ethylene glycol with single-walled carbon nanohorn inclusions. The thermal conductivity and viscosity was found to increase with respect to nanohorn loading. Maximum thermal conductivity enhancement of »11% at a nanohorn loading of 1.5 vol% was obtained in this...

In the present study, we report the effective thermal conductivity and rheological behavior of ethylene glycol with single-walled carbon nanohorn inclusions. The thermal conductivity and viscosity was found to increase with respect to nanohorn loading. Maximum thermal conductivity enhancement of ~11% at a nanohorn loading of 1.5 vol% was obtained i...

In the present work, we report the effective thermal conductivity of ethylene glycol and water with graphene nanoplatelets. Sodium deoxycholate, a bile salt was used as the surfactant to prepare stable nanofluid dispersions. Stability tests were performed using UV-Vis absorption spectrometry and zeta potential to monitor the stability of the prepar...

In Section 2.1 of the above article, the basefluid is mentioned as ‘H2O-EG (30:70)’ which is incorrect. The corrected statement is ‘H2O-EG (70:30)’.

As per Montreal Protocol R22 is to be phased out by 2030 AD in all Article 5 countries. Propane (R290) is a viable alternative for R22, but it is flammable. Hence attempts are made to reduce the charge quantity. This paper presents an experimental performance study of a split air conditioner with propane, as a substitute for R22. A split air condit...

This paper presents the investigation on the charge optimization of a split air conditioner designed for R22 but charged with R290 as an ecofriendly alternative. Initially a baseline test was conducted with R22 as the refrigerant. Then R290 was charged and the refrigerant quantity, capillary tube, and condenser tube optimizations were done based on...

In the present work, we report the thermophysical properties of ethylene glycol and water mixture based silver nanofluids. The thermo physical properties such as thermal conductivity, viscosity, density and specific heat are measured using KD2 Pro thermal properties analyser, capillary viscometer, electronic weighing balance and differential scanni...

In this study, the effects of deep cryogenic treatment (DCT) on the mechanical and tribological properties of AISI D3 tool steel were investigated together with a systematic correlation between their hardness and wear resistance. It was found that conventionally heat treated AISI D3 tool steel samples were significantly hardened via an additional D...

This experimental study investigates the effects of cryogenic treatment on the corrosion resistance and thermal expansion of En 52 and 21-4N valve steels. The materials are subjected to deep cryogenic treatment and the corrosion behaviour and thermal expansion are compared with that of the conventional heat treatment. The valve steel samples are sl...

A series of reciprocating wear tests were performed on the deep cryogenically treated and conventionally heat-treated samples of 100Cr6 bearing steel to study the wear resistance. The worn surfaces as well as the wear debris were analyzed by scanning electron microscopy. The improvement in wear resistance of the deep cryogenically treated samples r...

R22 has been used as a refrigerant in residential air-conditioners and heat pumps for many decades. Even as the Montreal protocol set the phasing out of R22 due to its ODP, many alternatives to R22 are found in published literature. The M20 refrigerant mixture is one such alternative with specific advantages. This paper presents the heat transfer c...

Nanofluid with nanoparticles at low- volume fractions in liquid, enhances the thermal conductivity of the fluid. Thus, they are potentially useful for augmenting the heat transfer in thermal systems. Focusing mainly on low concentration with well-dispersed nanoparticles in water or ethylene glycol, many researchers have reviewed the measurement tec...

This paper presents an approach to optimize the deep cryogenic treatment (DCT) process parameters for 100Cr6 bearing steel, based on the Taguchi method with grey relational analysis. The DCT parameters considered for the optimization are, the cooling rate, soaking temperature, soaking time, and tempering temperature, with the quality targets of dim...

The two-phase heat transfer coefficients of R404A and R134a in a smooth tube of 7.49-mm inner diameter were experimentally investigated at low heat and mass flux conditions. The test section is a 10-m-long counter-flow horizontal double-tube heat exchanger with refrigerant flow inside the tube and hot fluid in the annulus. The heat transfer coeffic...

The purpose of this study is to examine the effect of cryogenic treatment on the enhancement of the wear resistance of 100Cr6 bearing steel. The study also aims to reveal the underlying mechanisms responsible for the enhancement of wear resistance by deep cryogenic treatment (DCT) at -185°C. The wear behaviour is assessed by a reciprocatory frictio...

To investigate the convective heat transfer of nanofluids, experiments were performed using silver–water nanofluids under laminar, transition and turbulent flow regimes in a horizontal 4.3mm inner-diameter tube-in-tube counter-current heat transfer test section. The volume concentration of the nanoparticles varied from 0.3% to 0.9% in steps of 0.3%...

The following technical paper examines the effect of cryogenic treatment on the impact behavior of case-carburized En 353 steel. A comparative study on the effect of deep cryogenic treatment (DCT), shallow cryogenic treatment (SCT), and conventional heat treatment (CHT) on impact properties was also made by means of charpy impact test as per ASTM s...

Experimental investigation on flow boiling heat transfer characteristics of R404A (R125/R143a/R134a) was carried in a smooth horizontal tube of 7.49-mm inner diameter. The tested conditions were similar to those present in the evaporator of supermarket display cases, refrigerated cabinets, laboratory freezers, etc. The heat transfer coefficients al...

R22 has been generally accepted as the most suitable refrigerant for air conditioners, due to its favorable thermodynamic properties. However, R22 is a controlled substance under the Montreal protocol. M20 is a HFC/HC refrigerant mixture that can be used as a substitute for R22. This paper presents experimental investigation on the performance comp...

This experimental study investigates the effects of cryogenic treatment on the tensile behaviour of En 52 and 21-4N valve steels at room and elevated temperatures. The materials are subjected to shallow cryogenic treatment (SCT) at 193 K and deep cryogenic treatment (DCT) at 85 K and the tensile behaviour is compared with that of the conventional h...

The effect of cryogenic treatment on the microstructure and wear resistance of X45Cr9Si3 and X53Cr22Mn9Ni4N valve steels is investigated by conducting an optical and scanning electron microscopy (SEM) study and reciprocating wear test (ASTM standard G-133). The materials are subjected to shallow (193 K) and deep cryogenic treatment (85 K), and the...

SYNOPSIS Maintaining good Indoor Air Quality inside air-conditioned spaces demands more fresh air for ventilation. This in turn increases the heat load on the evaporator coil. For minimising this additional load, a heat recovery unit called an enthalpy wheel is introduced to exchange sensible and latent heat between the fresh air and the return exh...

R22 being a HCFC is to be phased out soon as per the Montreal protocol. This paper presents the experimental performance study of an air-conditioner retrofitted with M20 (a refrigerant mixture of R407C, R600a and R290 in the mass fraction 80:10.96:9.04 respectively). M20 is considered as a substitute for R22 in window air-conditioners with mineral...

This paper deals with the optimisation of the deep cryogenic treatment process for 21-4N valve steel to maximise the tensile strength, hardness and wear resistance using Grey-Taguchi method. The factors considered for the optimisation are the cooling rate, soaking temperature, soaking period and aging temperature, each at three different levels. Ni...

Polyalkaline glycol is used as the lubricant with R134a in automobile air conditioning systems and it is well known that PAG oil is highly hygroscopic in nature. Presence of moisture in the system may detoriate the system and its performance. Hence PAG oil is replaced with conventional mineral oil. In the present study, a new refrigerant blend R134...

This article presents an experimental investigation where the thermal conductivity and viscosity of silver-deionized water nanofluid is measured and studied. The mixture consists of silver nanoparticles of 0.3, 0.6, and 0.9% of volume concentrations and studied for temperatures between 50°C and 90°C. The transient hot-wire apparatus and Cannon-Fens...

The commonly used refrigerant in unitary type air conditioners is R22 and its phase out schedule in developing countries is to commence from 2015. Many alternatives to R22 are found in published literature in which R407C has similar characteristics to those of R22 except for its zeotropic nature. However, R407C which is an HFC is made compatible wi...

The effect of the cooling performance of a copper metal foam heat sink under buoyancy-induced convection is investigated in this work. Experiments are conducted on copper metal foam of 61.3% porosity with 20 pores per inch. The pressure drop experiment is carried out to find the permeability and foam coefficient of the porous media. It is found tha...

This study investigated the optimization of the deep cryogenic treatment for En 52 valve steel using the Taguchi method in combination with the Grey relational analysis. The factors considered for the optimization are the cooling rate, soaking temperature, soaking period, and tempering temperature, each at three different levels. The mechanical pro...

This article presents the measurement of thermal conductivity and viscosity of nanofluids experimentally. Silver nanoparticles dispersed in water with volume concentrations of 0.3, 0.4, 0.6, 0.8, 0.9, and 1.2 vol% are used in the present study. A transient hot-wire apparatus is used for measuring the thermal conductivity of nanofluids and a Cannon-...

The flow boiling heat transfer coefficients of R-134a/R-290/R-600a (91%:4.068%:4.932% by mass) refrigerant mixture are experimentally arrived in two tubes of diameter 9.52 and 12.7mm. The tests are conducted to target the varied heat flux condition and stratified flow pattern found in evaporators of refrigerators and deep freezers. The varied heat...

A steady state thermodynamic model for an air—cooled finned—tube condenser, used in a typical deep freezer vapour compression system, operating with pure and refrigerant mixtures has been developed using finite difference method. The heat transfer aspects in the condenser are treated uniquely for superheated, two—phase and subcooled regimes and stu...

A colloidal mixture of nano-sized particles in a base fluid, called nanofluids, tremendously enhances the heat transfer characteristics of the original fluid, and is ideally suited for practical applications due to its marvelous characteristics. This article addresses the unique features of nanofluids, such as enhancement of heat transfer, improvem...

This experimental study investigates the wear resistance improvement in En 52 and 21-4N valve steels through shallow and deep cryogenic treatment using a reciprocatory friction and wear monitor as per the ASTM standard G-133. It has been observed that the wear resistance of En 52 and 21-4N has improved by 81.15% & 13.49% respectively, due to shallo...

The integrity of the electrical insulation is of greatest importance in the reliability of high voltage equipment. For the development of high temperature superconductivity power equipments the cryogenic insulation technology need to be established. The present research work aimed to develop practical and reliable methods that can diagnose the degr...

This paper analyses theoretically the heat transfer characteristics of fin-and-tube evaporators with R22 and R407C/R290/R600a (M20) refrigerant mixture. The heat transfer coefficient and the pressure drop of refrigerant for two-phase flow are calculated using existing correlations from published literature. The simulation algorithm is based on the...

The steady state thermofluid behavior of a visi-cooler has been mathematically modeled using a distributed parameter technique for R-12 and R-134a/R-290/R-600a mixtures. The pressure drop in condenser and evaporator tubes, pressurevolume diagram, temperature glide, compressor power, and per day energy consumption for various operating conditions ha...

R22 is an hydrochlorofluorocarbon widely used in refrigerant and air conditioning plants and although it has a low ozone depletion potential (0.05), it is necessary to consider the large amount that commonly escapes from commercial units to the atmosphere. This paper presents experimental investigation on the performance of a window air conditioner...

An experimental investigation was conducted for a better understanding of fatigue and fracture behaviour of carburized steel used in the manufacture of vehicle transmission elements such as crown wheel and pinion. An attempt was made to study the fatigue strength of Err 353 based on failure at 107 cycles after subjecting to three different treatmen...

The influence of nucleation on the flow boiling heat transfer coefficient of R-134a/R-290/R-600a refrigerant mixture is experimentally studied in a smooth horizontal tube of 12.7 mm diameter. The heat transfer coefficients are experimentally measured for stratified flow patterns under a varied heat flux condition; a condition found in the evaporato...

R134a has been accepted as the single major refrigerant in the automobile industry and it has been used worldwide. But, the problem associated with it is the use of the PAG oil as the lubricant. Unlike the conventional mineral oil, the synthetic PAG oil used with R134a is highly hygroscopic in nature. The PAG lubricants come with different additive...

An experimental study on in-tube flow boiling heat transfer of R-134a/R-290/R-600a refrigerant mixture has been carried out under varied heat flux test conditions. The heat transfer coefficients are experimentally measured at temperatures between −8 and 5°C for mass flow rates of 3–5gs−1. Acetone is used as a hot fluid which flows in the outer tube...

The effect of shallow cryogenic treatment (SCT) and deep cryogenic treatment (DCT) on the microstructure of En 31 bearing steel is studied in the present work. En 31 bearing steel subjected to cryogenic treatment showed more hardness than the conventionally heat treated steel. Fractography analysis of the cryogenic treated steel carried out using s...

A detailed experimental investigation is carried out to study the flow boiling heat transfer behavior of R-134a/R-290/R-600a (91%/4.068%/4.932% by mass) refrigerant mixture in smooth horizontal tubes of diameter 9.52 and 12.7mm. The heat transfer coefficients of the mixture are experimentally measured under varied heat flux conditions for stratifie...

The present work is an experimental study of steady state convective heat transfer of de-ionized water with a low volume fraction (0.003% by volume) of copper oxide (CuO) nanoparticles dispersed to form a nanofluid that flows through a copper tube. The effect of mass flow rate ranging from (0.0113 kg/s to 0.0139 kg/s) and the effect of inlet temper...

The fiber which serves as a reinforcement in reinforced plastics may be synthetic or natural. Past studies show that only artificial fibers such as glass, carbon etc., have been used in fiber-reinforced plastics. Although glass and other synthetic fiber-reinforced plastics possess high specific strength, their fields of application are very limited...

A mathematical model has been developed to simulate the in-tube flow boiling heat transfer process of a refrigerant mixture under a variable heat flux boundary condition. The one-dimensional steady-state evaporation model is focused at a low heat flux and mass flow rate condition that is found in evaporator tubes of supermarket refrigerators and de...

The flow boiling heat-transfer coefficients of R-134a and R-134a/R-290/R-600a zeotropic refrigerant mixture were experimentally measured in a smooth horizontal tube of a 9.52-mm diameter. The values were compared for similar working pressure, reduced pressure, and liquid entry saturation temperature. The tests were conducted under varied heat flux...

This article reviews the studies of flow boiling heat transfer of refrigerants with a stratified flow pattern in smooth horizontal tubes. The paper addresses the mechanisms of flow boiling and highlights the importance of nucleate boiling in a stratified two-phase flow. Further, the article addresses some of the familiar correlations used to predic...

This paper presents the measurement of the temperature dependent property such as the thermal conductivity and viscosity of silver nanoparticles suspended in water as nanofluids. The experiments were carried out over the temperatures ranging from 50°C to 90°C with 0.4%, 0.8%, and 1.2% volume concentrations. A transient hot-wire apparatus is used fo...

The flow boiling heat transfer study of R-134a/R-290/R-600a refrigerant mixture is carried out in a vertical helical evaporator test section. The test section is immersed in an agitated ethylene glycol-water bath maintained at constant temperature. An aluminum test section with a height of 0.22 m, tube inside diameter of 6 35 mm, outside diameter o...

HFCs are the leading options for replacing R22 in air conditioning applications due to the Montreal Protocol. Among the HFCs, one of the more promising refrigerants is R407C, a zeotropic refrigerant mixture with a glide temperature difference of roughly 6°C. However, R407C could not be used as a drop-in substitute since HFCs are immiscible with con...

To develop a high temperature superconducting (HTS) transformer, the insulating materials used should be characterized at cryogenic environment. An attempt has been made to measure the AC, standard impulse and bi-directional oscillatory non-standard impulse breakdown strength and the corresponding partial discharge. Kraft paper and press paper used...

The effect of cryogenic treatment on the distribution of residual stress in the case carburized steel (En 353) was studied using X-ray diffraction technique. Two types of cryogenic treatment: shallow cryogenic treatment (193 K) and deep cryogenic treatment (77 K) were adopted, as a supplement to conventional heat treatment. The amount of retained a...

Cryogenic treatment is an inexpensive supplementary process to conventional heat treatment, which improves the tribological properties of steels. A study has been made on the effect of cryogenic treatment on En 31 steels done at different stages of heat treatment. It is observed that through cryogenic treatment the wear can be decreased by a maximu...

Deep cryogenic treatment (DCT) is a one time permanent process, carried out on steel components in such a way that the material is slowly cooled down to the cryogenic temperature, after which it is held at that temperature for a specified period of time and is heated back to room temperature at a slow rate followed by low temperature tempering. The...

An investigation on in-tube flow boiling heat transfer of R-134a/R-290/R-600a (91%/4.068%/4.932% by mass) refrigerant mixture has been carried out in a varied heat flux condition using a tube-in-tube counter-flow test section. The boiling heat transfer coefficients at temperatures between -5 and 5C for mass flow rates varying from 3 to 5 g/s were e...

The crown wheel and pinion represent the most highly stressed parts of a heavy vehicle; these are typically made of 815M17 steel. The reasons for the frequent failure of these components are due to tooth bending impact, wear and fatigue. The modern processes employed to produce these as high, durable components include cryogenic treatment as well a...

Countries that have ratified Montreal Protocol have to phase out HCFC22 in the near future due to its ozone depleting potential (ODP) and hence new eco-friendly refrigerants are being evolved as substitutes. At Present HFC407C is one of the promising drop-in substitutes for HCFC22. But it is immiscible with mineral oil and hence polyol ester (POE)...

The crown wheel and pinion are the critical components in the transmission system of an automobile. Failure of these components has drastic effect on the vehicular movement. This in turn leads to increased downtime for repairs. The cost of these components adds to the criticality in addition to its function. A fractured gear was subjected to detail...

HCFC22, the commonly used refrigerant in window air-conditioner is to be phased out completely due to Montreal Protocol regulations. Hence the search for drop in substitutes to retrofit window air-conditioner is of current interest. Capillary tube is commonly used in domestic refrigeration and air conditioning systems as expansion devices. This pap...

HCFC22, one of the widely used refrigerants in window air conditioners must be phased out soon as per the Montreal protocol. Presently, HFC407C is considered as a potential drop in substitute for HCFC22, but retrofitting HCFC22 systems with HFC407C with polyol ester oil (POE) is a major issue as HFC407C is immiscible with mineral oil. The miscibili...

All mechanical components that undergo sliding or rolling contact are subject to some degree of wear. So wear is an important tribological phenomenon while studying the failure of components. The observed frequent failure of crown and pinion due to wear and fatigue lead to this study on effect of cryogenic treatment on the wear resistance of case c...

The environmental concerns with the impact of refrigerant emissions lead to the importance in identifying a long-term alternative to meet all requirements in respect of system performance and service. Even though HFC134a and HC blend (containing 55.2% HC600a and 44.8% HC290 by weight) have been reported to be substitutes for CFC12, they have their...

In the event of chlorofluorocarbon (CFC) phase out, identifying a long term alternative to meet all our requirements in respect of system performance and service is an important area for research in the refrigeration and air conditioning (RAC) sector. Even though HFC134a and the HC blend (containing 55.2% HC600a and 44.8% HC290) have been reported...

Conversion of CFC12 systems to eco-friendly ones will be a major thrust area for refrigeration sector in the near future. As and when an existing CFC (chlorofluorocarbon) system has to be recharged it is advisable to retrofit the system with an eco-friendly energy efficient refrigerant. Presently two potential substitutes, namely, HFC134a and HC bl...

Stringent functional requirements in comfort air-conditioning have initiated a need for reliable load calculation means in HVAC industry. The load calculation generally involves consideration of many factors making manual calculation laborious, especially, when the space to be conditioned is complicated and large. Though lots of software programs a...

In a refrigerant compressor, improvement in performance such as reduction of various electrical and mechanical losses, reduction of gas leakage, better lubrication, reduction of suction gas heating etc. can be achieved by maintaining a low temperature rise inside the compressor. Proper selection and location of an internal over load protector relay...

The search for alternative refrigerant to phase out CFC12 has picked up momentum in the last few years. It is more significant in the context of retrofitting CFC12 system as the deadline for the above as per Montreal Protocol is fast approaching. Pure refrigerants and mixtures of both HFCs (Hydroflourocarbons) and HCs (Hydrocarbons) are available a...