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A special type of flexure bearings are installed to support a compressor motor and a displacer within a cryocooler which is used in space applications. The fatigue life of spring is a critical factor for such applications, to ensure that the cryocooler does not fail. The flexure spring is used in the setup of an eccentric type of flexure bearing. The present study analyzes various significant parameters and properties in selecting the best suitable material to achieve finite-fatigue life. To avoid a failure of such critical component, batch testing is carried out. The three materials which are compared with respective SN-curve are a] beryllium copper, b] Stainless Steel (3 0 4) and c] Titanium. The study has been carried out to find the best suitable material for flexure bearing. Finite Element Analysis (FEA) is used to understand flexure springs stress and displacement.

Small-scale power generation using heat energy from hydrocarbon (HC) fuels is a proven technology. In this study, we analyzed 2D flame development in meso-scale Swiss roll combustor (SW). A mixture of 60% butane and 40 % propane was used (0.25-0.55 l/min). During all the analyses, equivalence ratio (1.1) was kept constant by adjusting air quantity against fuel quantity. The effect of increase in the mixture velocity on the development of flame shapes/patterns was monitored. We found different patterns of flame, e.g., Planar, Concave, conical, with the increase in mixture velocity. Increase in combustion chamber temperature was also noted. No Flashback was observed and blowout was observed with very high mixture velocity. Combustion chamber temperatures were found to be increasing with the increase in mixture velocity at the same equivalence ratio. Elongation of the flame was observed because of the increased flow velocity. Heat recirculation to the reactants enhances flame characteristics.

Solar distillation plants are utilised for providing desalinated water to small communities close by seaside remote terrains. The construction of the still is comparatively easy as the material req...

In last few years in automobile sector there is a emerging need of an alternative fuel because of depletion of the stock of fossil fuels in all over the world. Bio-diesel in this regard contested a strong alternative to the conventional fuels. Bio-diesel contains 9-10% higher oxygen and higher cetane number which allows its good combustion in the combustion chambers of the engine. But poor hot flow and cold flow properties of biodiesel restricts their applications in the field of automotives. So the blends of biodiesel in percentage with diesel and ethanol as an properties enhancer additives are used in the biodiesel/diesel blend. Reduced viscosity, higher calorific value, improved flash and fire point and enhanced cold flow properties of the blends with ethanol as an additive, enhanced the combustion and reduced harmful emissions from the engine. Experimental work presented in this paper is by considering cottonseed biodiesel as raw feedstock blended with diesel and 5% ethanol. Properties were investigated experimentally as per IS 1448 standards. Trials were conducted on the single cylinder diesel. Results show that there are significant improvements in the properties of the blend, performance, combustion and reduced harmful emission from the engine. Experimental investigation reported that ethanol as an additives in the blends of cotton-seed biodiesel with diesel reduces kinematic viscosity by 7%, cold flow properties by 9% to 10% . But on the other hand but density of the blend is increased by 3% and higher heating value is decreased by 9%.

The focus of research in automobile engineering is shifted towards the reduction of emissions and enhance in fuel economy of automobiles. Employing magnetic field to fuel line carrying hydrocarbon ...

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 c...

Oil remains the world’s leading fuel, accounting for a third of global energy consumption. Global oil consumption growth averaged 1.6 million barrels per day (Mb/d). The demand of energy is increas...

The present study discusses the erosion of aluminium pipe using nano and micro particles. The Computational Fluid Dynamics (CFD) analysis using ANSYS-fluent is done for the prediction of the erosio...

The working principle of thermo-acoustic engines depends on the temperature, velocity and pressure gradients which were developed across the regenerator during operation. Hot heat exchanger and mai...

Erosion is one of the vital factors to consider for damage of solid-liquid, solid-gas multiphase flow system. The presence of solid particles in the fluid domain initiates the erosion. This paper focuses on the erosion analysis methods. Different erosion models for analytical and numerical investigation are discussed along with experimental test processes for erosion. Further, possible techniques used for analyzing the eroded surfaces are discussed. This study will be helpful for researchers working on erosion phenomena which can find erosion by analytical, numerical as well as experimental ways. Erosion prediction before implementation will save the system performance degradation. Lastly, consideration of the factors like temperature, impact angle variation during the flow and complex geometry is recommended for future study.

Considering a cryocooler for space applications, a special type of a flexure spring is fitted to assist the compressor motor and a displacer for liner motion thereby removing vibrations, frictional losses, and wear & tear. In the context of the critical application, the important physical parameter i.e., fatigue life of the flexure spring matters the most so that cryocooler does not fail during the operation. The present research study is an attempt to analyze the vital factors and attributes to determining the suitable material for accomplishing finite-fatigue life for the special flexure spring. A comprehensive analysis for material selection was conducted using the material options viz. a] AISI 304 Stainless Steel b] Beryllium Copper UNSC17200 c] Grade 5 Titanium (Ti-6Al-4V-3.7165-R56400) and d] AMPCOLOY® 944. Further, the materials stated were compared to their respective S-N curves. To decode the flexure spring’s performance evaluation, the parameters viz. load stresses, stiffness, displacement, geometrical configuration, etc. were analyzed using the Finite Element Analysis (FEA) package.

The mitticool refrigerator works on the principle of evaporative cooling which keeps the fruits, vegetables and dairy products fresh. Mitticool refrigerator works well in hot and dry weather without electricity. The current study investigates the efficiency of mitticool refrigerator with decrease in inner temperature with respect to outer wind velocity and relative humidity. The study is further extended to different compartments and walls of the refrigerator to calculate the performance of the mitticool refrigerator for different seasons. The results showed that the refrigeration effect achieved in the mitticool refrigerator depends on ambient temperature and humidity. The maximum refrigeration effect achieved in summer is 4.5 °C due to high Dry bulb temperature (DBT). The minimum refrigeration effect achieved in winter is 2.5 °C due to low DBT. It is also observed that in the rainy season, refrigeration effect is 3 °C due to high relative humidity. The refrigeration effect at day is higher and at night is slightly lower. Mitticool refrigerator gives better performance in the summer season.

Finite Element Analysis of a flexure bearing used in a cryocooler for space application is a very critical component in determining the working life of cryocoolers. The present study analyzes various significant parameters using the finite element analysis to achieve finite-fatigue life. The infinite fatigue life is necessary to ensure that cryocooler does not fail during the mission life of the satellite. Flexure bearing serves two purposes—(a) maintaining a mean position of a free-piston in linear compressor by providing desired stiffness and (b) avoiding radial deflection of the piston leading to wear and tear. The flexure bearing also ensures oil-less operation of linear compressor since the use of oil in cryocooler may lead to severe damage to the heat exchanger by freezing at cryogenic temperature. This paper considers various essential parameters optimized to achieve—(a) high stiffness (b) load stresses and (c) infinite fatigue life necessary for space application.

Flexure springs play pivotal role to ensure reliability and durability of the cryocooler compressors. The critical application of flexure spring intends to eliminate the wear, frictional losses and significantly vibrations. A parameter study was performed considering the design variables of a flexure spring to meet the requirements of the cryocooler compressors viz. complexity of the geometric configuration, radial and axial stiffness, fatigue life, material, etc. The parametric design approach was deployed using finite element analysis (FEA), to validate the same by experimental data to analyse the performance of the flexure spring. This paper also presents a comparative analysis of the design variables in terms of axial and radial stiffness, induced stress as well as the manufacturing methods’ considerations to optimize the design of a special purpose flexure spring for the cryocooler compressors. Furthermore, experimental study of the flexure spring was carried out in order to maximize the stroke.

Vapor compression refrigeration system is commonly used for air-conditioning and refrigeration. It is also used in domestic & commercial refrigerators and cold storage applications. Industrial sectors like refinery, petrochemical, chemical, pharma & pulp also benefit from it. The refrigeration system cools the process fluids to the desired temperature. The most commonly used process fluids are water, air, and brines. Irrespective of size and application of the system, all of them operate on common thermodynamic cycle called ‘Vapor compression refrigeration cycle’. Oil is used in compressors of refrigeration systems for lubrication, sealing, cooling, reducing pressure pulsations (leading to silencing effect) and for auxiliary functions like capacity control in screw compressors. Oil gets mixed with refrigerant and is discharged out from the compressor along with refrigerant at high pressure & temperature. Oil, if not separated from the discharge gas, can deteriorate heat transfer in heat exchangers in the refrigeration system. In extreme cases, if oil does not return back to compressor then compressor damage can happen. Therefore, separation of oil from refrigerant before the condenser is important. In this paper the conditions when oil separators are necessary in refrigeration systems are discussed. The paper presents a review of variety oil separation technologies used in different types of refrigeration systems. These technologies are based on fluid flow mechanisms involving velocity reduction, change of direction, gravity settling, centrifugal motion, demister pad, impingement separation and coalescing separation. Every technology has unique advantages and limitations. Construction and operation of commonly used oil separators, employing different technologies for oil separation are explained. Though article focuses on refrigeration systems, the concepts discussed are also applicable to any oil-gas separation systems

A research on different refrigerants with and without influence of the magnetic field is provided in this paper. The magnetic field degree viz is four gauss. The condenser exit row was 3000, 6000, 9000 and 12000 gauss. Magnetic fields at condenser exit lines are found to reduce the consumption of the compressor energy. Through applying magnet fields on R134a, compressor energy savings was observed up to 1.35%, 6.23%, 5.40% and 4.19%, respectively, in gauss levels of 3000, 6000, 9000 and 12000, while R152a savings in energy levels were up 13.10%, 15.59% and 25.86% and R407a saving in power up to 7.3%, 9.19%, 13.05% and 12.40%. The coolant R152a saves energy in contrast to other coolant compressors. As the magnetic field strength increases, a vapor refrigeration system decreases the energy consumption of the compressor.

Solid particles are the elements who originate the erosion of system component. These are either introduced during the process, for example in oil industries as sand particles or introduced by inte...

Thermal conductivity (k) is an important property of the fluid which contributes to the heat transfer. Presence of nanomaterial enhances the k of the base fluid and can be used as potential heat tr...

Thermo-acoustic engines are devices suitable to convert heat energy into acoustic energy and vice versa. In this paper, travelling wave thermo-acoustic engine was designed and fabricated for the op...

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.

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 use...

Hydrocarbon fuels have high energy density which is used to run small-scale mechanical systems. The present work emphasises on experimental investigations carried out on thermal characteris...

Biodiesel is world widely recognized as an alternative fuel to conventional diesel fuel in compression ignition engines. It has many advantages including reduction of exhaust gases emissions such as CO, SOx, NOx, and hydrocarbon, higher cetane number, reduced toxicity, safety, and improved CO 2 lifecycle. But the poor cold flow properties and higher viscosity of biodiesel limits there usage in the field of transportation sector. Biodiesel derived from different raw feedstock of plant based oils or animal fats contained a significant amount of saturated free fatty acids which increases viscosity, cloud point and pour point of biodiesel. These properties can be enhanced by adding an ethanol as an additive in the blends of biodiesel with diesel which can be further able to enhance the engine performance and reduce harmful exhaust emissions. In the present experimental investigation, an ethanol is added to Jatropha, Soybean, Palm, and Cottonseed biodiesel with diesel as an additive by 5% volume. Properties are investigated as per IS 1448 standards. Investigation reported that addition of ethanol as an additive reduces the kinematic viscosity, cloud point and pour point of blends of biodiesel. The test fuels B20E5 (20% biodiesel + 75% diesel + 5% ethanol) of Jatropha, Soybean, Palm, and Cottonseed biodiesel are tested on single cylinder,four stroke,VCR (Variable Compression Ratio) electric start diesel engine connected to eddy current dynamometer for various load conditions to evaluate performance analysis of the engine. The performance analysis of investigation shows that there is an improved BP (Brake Power), increased BSFC (Brake Specific Fuel Consumption) and increased BTE (Brake Thermal Efficiency) for various loads on engine for Jatropha, Soybean, Palm and Cottonseed biodiesel- diesel blend with ethanol as an additive

The refrigeration and air-conditioning system contribute significantly to building energy consumption. Therefore, it is necessary to develop new technologies that can achieve a higher coefficient of performance (COP). Employing a magnetic field (MF) on the condenser tube (between the condenser outlet and the capillary tube) is a new technique that helps in improving efficiency and cooling capacity of air-cooled vapour compression cycle (VCC) water chiller. In this work, four pairs of the permanent magnet of 3000 G field strength were installed on the condenser tube (between exit of the condenser and inlet of the capillary tube) of the VCC water chiller test setup. The performance of the test setup was compared by applying and removing an MF from the condenser tube to estimate an enhancement in the VCC water chiller system with an MF. Experiments were carried out using R404A as a primary refrigerant in the VCC system. This work discusses the outcomes of magnetic flux applied to the condenser tube at various locations of VCC on COP and power consumption of the water chiller unit. The percentage growth in refrigeration effect ranged between 0.58 and 8.82, and a higher value of the refrigeration effect of 8.82 was found by using the first magnet pair. Experimental outcomes show that compressor power consumption decreased by 4.43% with an increase in the number of magnet pairs from 1 to 4. The VCC system performance was improved by 8.94%. (C) 2017 Elsevier B.V. All rights reserved.

Looking at the present need of small scale power generation to run devices like small thrusters, cellular phones, laptops etc. attempts were made to develop small scale power generating devices. But issues increases with downsizing of the small scale power generators. Present work mainly focuses on the experimental investigations carried out on different materials (i.e. Aluminum, copper, stainless steel and brass) which were manufactured as one turn Swiss roll combustor. Studies were carried out on the Swiss roll combustor for fixed depth of 20mm. Reactants channel dimension and Products channel dimensions were 2mm and 3mm respectively. During the experiments conducted parameters varied were equivalence ratio and materials of the combustor. Parameters measured during the experiments were flame stability limits, external surface temperatures, combustion space/room temperatures. External surface heat loss to atmosphere was calculated for different values of equivalence ratio. Flame was observed stable successfully during all the experiments conducted. Heat transferred on all the external surfaces from the combustion space can be used as heat input to thermal electric devices. Higher heat content values were observed for SS material and lower values for Br material. Equivalence ratio equal to 1.068 was found to be the best at which maximum temperatures and heat content observed for all the materials. Maximum total heat content of 39.21W was observed for SS material. Lean limit temperatures were observed to be higher compared to rich limit temperatures.

Static magnetic field produced by permanent magnets applied to the fuel lines of internal combustion engines reduces viscosity of fuel, leading to better atomisation and improved carburetion, which enhances the combustion of the fuel and performance of the engine. Increased combustion reduces HC (hydrocarbon) and CO (carbon monoxide) % emitted from exhaust. Experiments in present work emphasise the effect of use of multiple pairs of permanent magnets of 3000 gauss intensity each, installed to the fuel line of four-stroke SI engine. It is evident from experiments that with increasing number of pairs of magnet lead to decrease in emissions. Results validate the impact of magnetic field strength on emissions from exhaust. Experimental results show that with application of magnetic flux to the fuel at constant load of 2 kg, there is 17.46% reduction in CO emissions, 18.048% reduction in HC and 1.118% increase in CO2 from the exhaust on the use of 5 pairs of magnets.

Application of magnetic flux (MF) on the fuel line of diesel engines is a promising technique to enhance the performance of the engine. In this work, MF was applied by placing neodymium magnet pair...

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...

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.

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.

This paper presents experimental investigations carried out to study the effect of magnetic field on energy savings in vapour compression system. Application of magnetic field to fluid flow breaks the molecule resulting in a decrease in the viscosity of the fluid. This drop in the viscosity reduces the pumping power required by the compressor as well as enhances the heat transfer rates in the condenser and evaporator due to increased mass flow rates. The net impact is improvement in the COP of the system. Considering the number of refrigerator and air conditioning systems sold globally every year any improvement in the COP could considerably save the energy bills as well as the energy requirement. The main benefit of this investigation is improvement in the system performance improvement in Evaporator capacity or drops in compressor power or increased COP at no cost i.e. no additional input energy. Only cost involved is the initial cost of magnets to be procured for applying suitable magnetic field. The present work was focused on first establishing the effect of magnetic field on the performance of the vapour compression system and then investigating the impact of magnetic-field strength on COP. The magnetic field strength was varied by increasing the number of magnet pairs applied to the liquid line (from condenser outlet to entry of expansion valve). The COP was initially measured without application of magnetic field, and then magnetic field applied to liquid refrigerant was increased by increasing the number of the magnetic pair from 1 to 5. The strength of each magnetic pair was 3000 gauss. The result obtained showed improvement in COP of the system under investigation. The COP of the system increased up to13.13% for R134a and 21.87% for R600a refrigerant.

Solar energy is available in abundant quantity which can be utilized for thermal and power generation applications. The maximum solar energy extraction for application is challenging. This review focuses on the performance enhancement of parabolic trough collector. Heat transfer through absorber tube, various nanofluids with concentration is stated. Thermal efficiency increases due to the use of parabolic collector with booster reflector and glass cover over the system performance. The complex 3D analysis (ANSYS) gives accurate distribution of heat flux over the absorber tube.

Increase in the world energy demand has made renewable energy source as one of the best option. It is finding wide utility in comparison with the other sources of energy. Solar energy is one of the major source of renewable energy. The abundance of solar energy in India makes it highly desirable to exploit but due to the limitations of technology, only a fraction of the energy can be extracted and used. This paper describes a concept for solar detection sensor implementation in Photo-Voltaic (PV) dual-axis solar tracking systems. The system uses only three units of identical light-detecting- resistors (LDR) arranged on the three sides of tetrahedron geometry and is able to track the light source position at the strongest intensity of visible light. On the basis of comparative study of outputs of all the three LDRs, the panel will tilt so as to get maximum output from the system. This system results in a wide field of view with minimum error and also has advantages in terms of sensor quantity, size of the system, accuracy and effectiveness.

Electric vehicles are important in today’s world to reduce pollution. The demand for electric vehicles is increasing day by day. The major component is the battery for an electric vehicle which gives the power to drive motor and drives the vehicle. Continuous operation of the vehicle causes the battery to heat and while heating there are some flammable gases released which may cause a fire. The heating of batteries reduces the performance of the vehicle and reduces the efficiency, therefore there is a need for cooling techniques to keep the temperature of batteries below the critical temperature for safe operating conditions. The present study emphasizes various cooling techniques used for the battery thermal management system. Cooling improves the performance of the battery and reduces the temperature of the battery. It helps in maintaining the temperature of the battery at the desired level. Before cooling the battery, it is necessary to study the thermal behavior of the battery. Various aspects of the thermal behavior are also reported in the paper and the problems associated with the time required for charging the batteries are also discussed.

Evaporative cooling is one of the techniques to lower the ambient air temperature according to the requirements. The technique includes the injection of moisture in the coming air, thus increasing its specific humidity. This technique can cool the air up to wet bulb temperature of the incoming air. In the recent past, the techniques are developed to lower the temperature of air without addition of moisture in the incoming air. These techniques demonstrate that the incoming air temperature can be approached near the dew point temperature of the incoming air. The present paper essentially focuses on the recent theoretical and experimental research of dew point evaporative coolers. Different flow configurations of heat exchange mediums, optimization of geometrical parameters, performance parameters (wet bulb and dew point effectiveness), energy efficiency ratio and energy saving potential are the key elements to study the prospects of dew point evaporative coolers over the conventional refrigeration systems operated by mechanical means. Dew point evaporative cooling technology is environmental friendly and has the potential in reducing the impact on earth due to global warming.

Biodiesel is a biodegradable and non-toxic alternative fuel produced from various feedstocks of vegetable oil and animal fats and used as an alternative fuel in the transportation sector such as automotive, marine and small aircraft. The higher viscosity of biodiesel causes serious problems when it is used in the conventional engine without modification. Considering this problem the study has been carried out towards two objectives. The first objective is to identify the different feedstock of biodiesel and to study the variation of kinematic viscosity as a function of temperature and blend ratio with diesel fuel. The second objective is to correlate and develop the mathematical model of variation of kinematic viscosity as a function of temperature and blend ratio with diesel fuel by using non–linear regression analysis. Test fuels used were a conventional diesel, neat biodiesel of Cottonseed, Palm, Soybean and Jatropha oil, and their blends with blending ratio of 20, 40, 60 and 80% with diesel fuel. The blends were prepared on the volume basis and viscosities were measured as per IS: 1448 [P: 25]-1976 test methods. Equation given by Arrhenius and studied by Grunberg and Nissan was used to predict the viscosities of the biodiesel blends. For all blends of Cottonseed, Palm, Soybean and Jatropha oil biodiesel, it is reported that, there is an excellent agreement between the measured and predicted values of the viscosities and have an absolute maximum error up to 0.001. The viscosities of the test fuels were found to decrease linearly with increasing temperature and decreasing blend ratio.

A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2 W at 120 K and 0.5 W at 60 K cooling capacity for the two-stages and input power of less than 120 W. The Cryocooler achieved a minimum temperature of 40.7 K at stage 2. (C) 2017 Elsevier Ltd. All rights reserved.