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The present paper reports the performance of a popular refrigerant R32 (Difluoromethane, CF2H2) experiencing the two phase injection process. Two phase injection process may lower the discharge temperature of a multistage compressor. In order to investigate the role and impact of two-phase injection on a compressor, a Scroll compressor is selected because scroll compressor has high tolerance for liquid refrigerant. A reputed compressor is chosen where all the operating conditions and specifications are available in public domain. The modelling and analysis of refrigeration system is carried out using a simple MATLAB code. Around 200 iterations were performed for four different condensing and evaporating temperatures. The maximum reduction in discharge temperature is found to be 44°C when compared to R410A used in the same system.

In search of a viable alternative to petrol and diesel, methanol, ethanol and biodiesel play an important role. Methanol and ethanol are traditional alternatives to petrol (gasoline) because of better engine performance and reduced emission of carbon monoxide, oxides of nitrogen (NOx), unburnt hydrocarbon (UBHC) and other harmful gases. This work represents the result of four sets of spark timings on engine performance and engine emissions when run on methanol and petrol. Exhaustive investigations are carried out on a variable compression ratio DTSi engine for both methanol and gasoline. Engine was run at full throttle and at a constant speed of 1600 RPM. The efficiency of the engine found to be enhanced with methanol fuel which has higher octane number and high laminar flame speed. Maximum efficiency was found to be ~25.45% and ~28.7% at compression ratio 10 for gasoline and methanol fuel, respectively. This is observed at 26°–24° BTDC (before top dead center) spark advance combination. Optimum compression ratio for gasoline and methanol is found to be 6.8 and 7.4, respectively, at this spark advance angle combination. Moreover, methanol fuel eventually emits lesser amount of CO, UBHC and NOx than gasoline under all experimental combinations.

In this current work, the outcome of four sets of spark timings on engine performance parameters is studied. CFD simulations are carried out on a variable compression ratio twin spark SI engine for both methanol and gasoline. Simulations were able to predict performance parameters with high accuracy. To simulate flow physics, combustion in the engine, ANSYS Fluent is employed. A parametric study of the effect of spark timing and compression ratio under methanol operation at 1600 RPM is performed. The results yield a promising strategy in deciding spark advance angle. Both methanol and gasoline show increased mean effective pressure at twin spark of 26°–28° BTDC.

Estimation of magneto-caloric effect is crucial to determine a material’s suitability for the desired operating conditions. The magneto-caloric effect can be measured in two ways-the magnetic entropy change and the adiabatic temperature change. These parameters are the prerequisites in evaluating a magnetic refrigeration system. In this work, an application is developed and tested for 3 materials (one Gadolinium and two Lanthanum alloys) using COMSOL multiphysics to estimate the final temperature of a Magneto-Caloric Material (MCM). The duration of the magneto-caloric effect is compared amongst 4 different cases of magnetic field change. Among the selected materials Gadolinium shows the highest adiabatic temperature difference of 12K at a field change from 0 to 5 tesla.

In this work, a set of computational investigation results of two-phase refrigerant flow through adiabatic capillary are presented. There are various sizes of capillary tubes that can be selected related to commercially available copper tubes. Earlier refrigerants and new refrigerants like R12, R22, R134a, R410A and R32 are used for the flow analysis. Homogeneous-equilibrium model is employed with user-defined properties of the refrigerants for computation using ANSYS CFX. Several important parameters can be predicted rapidly and accurately using this method such as refrigerant mass flow rate, vapor mass fraction, local Mach no. etc. The mean deviation in mass flow rate is found to be [Formula: see text]1.18% for the same length of capillary tube and the mean deviation of tube length is found to be [Formula: see text]1.48% for the same experimental mass flow rate with choked flow condition.

This work reports hydrogen adsorption properties of four different metal–organic frameworks (MOFs) namely Zn-BDC, Cr-BDC, Ni-DABCO, and Mg-DOBDC. Gravimetric hydrogen adsorption measurements are performed over a wide range of temperature (90 K to 298 K) and pressure (0 bar to 100 bar). At the lowest experimental temperature (90 K to 100 K) all the isotherms are saturated and the adsorption capacity is governed by pore volume. On the other hand, at room temperature the isotherms closely follow Henry’s law. Modeling of the excess isotherms is also done. Net adsorption isotherms, which can directly indicate the efficiency of porous adsorbent for storage, are also presented. In terms of volumetric efficiency, Mg-DOBDC MOF exhibits best storage capacity out of all the MOFs considered in this study.

Solar refrigeration may have applications in both developed and developing countries. Applications in developing countries such as air-conditioning, vaccine storage or large scale food preservation have been the subject of scientific research. Ammonia-water based system has good COP but generally vapor absorption refrigeration system requires high generator temperature and high circulating ratio aided by a powerful pump. Our objective was to trivialize the role of circulating ratio and simultaneously achieve higher COP. A prototype model was designed, fabricated in laboratory using scrap material and tested; performance of the unit has been analyzed. A parabolic solar trough was used as a source of heat. Various components were modeled in computer and analyzed using ANSYS. The performances and effectiveness of the unit was studied by determining refrigeration effect (RE) and coefficient of performance (COP).

Adsorption systems may find its application in refrigeration and air-conditioning, ice-making, water chiller etc. In conventional vapor compression refrigeration system, compressor is the main power consuming component. A vapor adsorption systemcan be feasible replacement for vapor compression refrigeration system. The main objective of this project is to design, fabricate and test a cost effective and laboratory scale vapor adsorption refrigeration system. An intermittent type vapor adsorption system is fabricated using some common stainless steel utensils, copper tube, an electric heater and a laboratory vacuum pump. The Refrigeration effect and COP of the system is determined from basic thermodynamic relations. Though COP is ~0.175 but it's able to bring down temperature of circulating water by more than 10°C.

Capillary tubes are simple narrow tubes but the phase change which occurs inside the capillary tubes is complex to analyze. In the present investigation, an attempt is made to analyze the flow of Isobutane (R-600a) inside the coiled capillary tubes for different load conditions by Homogeneous Equilibrium Model. The Length and diameter of the capillary tube not only depend on the pressure and temperature of the condenser and evaporator but also on the cooling load. The present paper investigates the change in dimensions of the coil capillary tube with respect to the change in cooling load on the system for the constant condenser and evaporator conditions. ANSYS CFX (Central Florida Expressway) software is used to study the flow characteristics of the refrigerant. Appropriate helical coil is selected for this analysis.

Industrial refrigeration is one of the most energy consuming sector. In conventional Vapor Compression refrigeration system, compressor is the major power consuming element. Vapor Adsorption refrigeration system is one of the best replacement for the Vapor Compression refrigeration system. Our main objective is to analyze, design and develop a Vapor Adsorption refrigeration system which is cost effective and environmental friendly. A prototype model that is capable of producing a temperature drop in closed evaporator chamber was designed, fabricated and tested. Activated carbon/Methanol pair is chosen as Adsorbent/Refrigerant pair. The system is analyzed in ANSYS 14.5 using the inlet conditions obtained from the experimental setup. The performances and effectiveness of the unit was studied by determining Refrigeration Effect (RE), Coefficient of Performance (COP) and explaining operational issues of the unit. The results obtained from the analysis and experiments have marginal difference in COP i.e. with an error percentage of 5.94%. The overall COP obtained is 0.34 through experiments and from analysis the COP obtained is approximately 0.32.

Reported in this paper is a case study on a normal vapor compression refrigeration system which is expected to be run by photovoltaic panels to utilize minimum grid power. A small 120 W refrigerator is fabricated out of commercially available components and run by an inverter and battery connected to solar photovoltaic panel as well as grid. Temperature at several points was measured and the performance was evaluated. The Coefficient of performance (COP) to run such refrigerator is estimated after numerical simulation of major components namely, evaporator, condenser and a capillary tube. The simulation was done to obtain an effective cooling temperature and the results were compared with measured temperatures. Calculation proves to be in conformity with the actual model.

In this paper, we report the synthesis of polymer coated palladium ( Pd ) nanoparticles through a single stage reduction of Pd 2+ ions by ethylene glycol. Polyvinyl pyrrolidone (PVP, MW 25,000) is used as a stabilizer. Self-assembled Pd nanoparticles (10–40 nm) were used in hydrogen adsorption studies. Gravimetric adsorption measurements were carried out in a pressure range of 0–26 bar at 293, 324, 364 and 392 K. Saturation for all isotherms was obtained within a few bars of pressure at all temperatures. Maximum hydrogen storage capacity observed was 0.58 wt.% at 324 K and 20 bar. Net adsorption calculations indicated that required tank volume (for storing a particular amount of hydrogen) can be significantly reduced by using a tank filled with Pd nanoparticle.