Predicting the temperature distribution and suction gas superheating of an oil-free linear compressor

It is well established that the volumetric and isentropic efficiencies of reciprocating compressors used for household refrigeration are significantly reduced by suction gas superheating. Moreover, excessive levels of temperature may affect the reliability of some components, such as the electrical motor. This paper reports a modeling approach to predict the temperature distribution in the gas and solid components of an oil-free linear compressor. A simulation model based on the finite volume method was used to solve the heat conduction in the solid components and gas flow inside the compressor. On the other hand, the compression cycle in the cylinder was solved with a transient lumped formulation, but in a coupled manner with the remainder of the solution domain. The prediction of the suction gas superheating obtained with the model was in good agreement with the measurements, despite discrepancies being observed in some solid components and in the gas path along the discharge system. The model does not require any experimental calibration and hence is suitable to analyze different compressor designs. To illustrate this, the model was applied to predict the temperature distribution with respect to two design parameters.

Download Full-text

Computational Calculation of Thermal Efficiency in a Space Radiating Fin for Tow Different Materials

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.110-116.23 ◽

2011 ◽

Vol 110-116 ◽

pp. 23-28 ◽

Cited By ~ 1

Author(s):

Mohammad Hadi Kamrava ◽

Farzad Bazdidi-Tehrani

Keyword(s):

Temperature Distribution ◽

Thermal Efficiency ◽

Analytical Methods ◽

Control Unit ◽

Thermal Control ◽

The Other ◽

Fin Efficiency ◽

Volume Method ◽

Computational Calculation ◽

Good Agreement

In all industries which are related to heat, suitable thermal ranges are defined for each device to operate well. Consideration of these limits requires a thermal control unit beside the main system. The Satellite Thermal Control Unit (STCU) exploits from different methods and facilities individually or mixed. The space radiating fin which is combined with a heat pipe can be used to transfer the excess heat from the satellite to outer free space. The finite volume method is employed to simulate numerically the temperature distribution in a space radiating fin and evaluate thermal fin efficiency. Final results are achieved for two different materials (Aluminum and Beryllium) and compared to each other. The present results are compared with the other analytical methods and good agreement is shown.

Download Full-text

Transient Heat Transfer Analysis of Alloy Solidification

Journal of Heat Transfer ◽

10.1115/1.3450059 ◽

1973 ◽

Vol 95 (3) ◽

pp. 324-331 ◽

Cited By ~ 15

Author(s):

J. C. Muehlbauer ◽

J. D. Hatcher ◽

D. W. Lyons ◽

J. E. Sunderland

Keyword(s):

Temperature Distribution ◽

Eutectic Composition ◽

Approximate Solutions ◽

The Other ◽

Heat Transfer Analysis ◽

Uniform Temperature ◽

One Dimensional ◽

Temperature Distributions ◽

Finite Slab ◽

Good Agreement

Approximate solutions are obtained for the temperature distribution and rate of phase change for the transient one-dimensional solidification of a finite slab of a binary alloy. The alloy is selected to avoid the eutectic composition so that solidification takes place over a range of temperatures. The slab is initially superheated and has a uniform temperature distribution. Solidification occurs after one surface is cooled by convection while the other surface is insulated. Temperature distributions are determined analytically and experimentally and are in reasonably good agreement.

Download Full-text

Effect of design parameters on stresses occurring at the tooth root in a spur gear pressed on a shaft

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/0954408921995292 ◽

2021 ◽

pp. 095440892199529

Author(s):

Fatih Güven

Keyword(s):

Internal Pressure ◽

Tangential Stress ◽

Spur Gear ◽

Design Parameters ◽

Interference Fit ◽

Gear Design ◽

Compact Design ◽

Fit Tolerance ◽

Moderate Stress ◽

Good Agreement

Gears are commonly used in transmission systems to adjust velocity and torque. An integral gear or an interference fit could be used in a gearbox. Integral gears are mostly preferred as driving gear for a compact design to reduce the weight of the system. Interference fit makes the replacement of damaged gear possible and re-use of the shaft compared to the integral shaft. However, internal pressure occurs between mating surfaces of the components mated. This internal pressure affects the stress distribution at the root and bottom land of the gear. In this case, gear parameters should be re-considered to assure gear life while reducing the size of the gear. In this study, interference fitted gear-shaft assembly was examined numerically. The effects of rim thickness, profile shifting, module and fit tolerance on bending stress occurring at the root of the gear were investigated to optimize gear design parameters. Finite element models were in good agreement with analytical solutions. Results showed that the rim thickness of the gear is the main parameter in terms of tangential stress occurring at the bottom land of the gear. Positive profile shifting reduces the tangential stress while the pitch diameter of the gear remains constant. Also, lower tolerance class could be selected to moderate stress for small rim thickness.

Download Full-text

Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽

10.3390/foods10071622 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1622

Author(s):

Wipawee Tepnatim ◽

Witchuda Daud ◽

Pitiya Kamonpatana

Keyword(s):

Temperature Distribution ◽

Electric Field ◽

Three Dimensional ◽

Development Stage ◽

Microwave Oven ◽

Computational Time ◽

Plastic Package ◽

Heating Uniformity ◽

The Cost ◽

Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

Download Full-text

The Numerical Analysis of the Velocity and Pressure Distribution of the Oil Film in Heavy Hydrostatic Thrust Bearing

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.541-542.658 ◽

2014 ◽

Vol 541-542 ◽

pp. 658-662

Author(s):

Jian Li ◽

Yuan Chen ◽

Yang Chun Yu ◽

Zhu Xin Tian ◽

Yu Huang

Keyword(s):

Mathematical Model ◽

Numerical Analysis ◽

Pressure Distribution ◽

Working Conditions ◽

Thrust Bearing ◽

Rotation Speed ◽

The Other ◽

Surface Load ◽

Oil Film ◽

Volume Method

To study the velocity and pressure distribution of the oil film in a heavy hydrostatic thrust bearing, a mathematical model of the velocity is proposed and the finite volume method (FVM) has been used to simulate the flow field under different working conditions. Some pressure experiments were carried out and the results verified the correctness of the simulation. It is concluded that the pressure distribution varies small under different rotation speed when the surface load on the workbench is constant. But the velocity of the oil film is influenced greatly by the rotation speed. When the rotation speed of the workbench is as quick as enough, the velocity of the oil film on one radial side of the pad will be zero, that is to say the lubrication oil will be drained from the other three sides of the recess.

Download Full-text

Responses of the Pheromone-Binding Protein of the Silk Moth Bombyx mori on a Graphene Biosensor Match Binding Constants in Solution

Sensors ◽

10.3390/s21020499 ◽

2021 ◽

Vol 21 (2) ◽

pp. 499

Author(s):

Caroline Bonazza ◽

Jiao Zhu ◽

Roger Hasler ◽

Rosa Mastrogiacomo ◽

Paolo Pelosi ◽

...

Keyword(s):

Bombyx Mori ◽

Binding Protein ◽

Binding Constants ◽

Isoamyl Acetate ◽

The Other ◽

Oxide Surface ◽

Binding Assays ◽

Pheromone Binding Protein ◽

Silk Moth ◽

Good Agreement

An electronic biosensor for odors was assembled by immobilizing the silk moth Bombyx mori pheromone binding protein (BmorPBP1) on a reduced graphene oxide surface of a field-effect transistor. At physiological pH, the sensor detects the B. mori pheromones, bombykol and bombykal, with good affinity and specificity. Among the other odorants tested, only eugenol elicited a strong signal, while terpenoids and other odorants (linalool, geraniol, isoamyl acetate, and 2-isobutyl-3-methoxypyrazine) produced only very weak responses. Parallel binding assays were performed with the same protein and the same ligands, using the common fluorescence approach adopted for similar proteins. The results are in good agreement with the sensor’s responses: bombykol and bombykal, together with eugenol, proved to be strong ligands, while the other compounds showed only poor affinity. When tested at pH 4, the protein failed to bind bombykol both in solution and when immobilized on the sensor. This result further indicates that the BmorPBP1 retains its full activity when immobilized on a surface, including the conformational change observed in acidic conditions. The good agreement between fluorescence assays and sensor responses suggests that ligand-binding assays in solution can be used to screen mutants of a binding protein when selecting the best form to be immobilized on a biosensor.

Download Full-text

Robust Design Techniques for Evaluating Fuel Cell Thermal Performance

ASME 2006 Fourth International Conference on Fuel Cell Science, Engineering and Technology, Parts A and B ◽

10.1115/fuelcell2006-97011 ◽

2006 ◽

Author(s):

Kenneth J. Kelly ◽

Gregory C. Pacifico ◽

Michael Penev ◽

Andreas Vlahinos

Keyword(s):

Fuel Cell ◽

Heat Generation ◽

Thermal Performance ◽

Gas Flow ◽

Internal Heat ◽

Flow Path ◽

Coolant Flow ◽

Design Parameters ◽

Fuel Cell Stack ◽

Path Design

The National Renewable Energy Laboratory (NREL) and Plug Power Inc. have been working together to develop fuel cell modeling processes to rapidly assess critical design parameters and evaluate the effects of variation on performance. This paper describes a methodology for investigating key design parameters affecting the thermal performance of a high temperature, polybenzimidazole (PBI)-based fuel cell stack. Nonuniform temperature distributions within the fuel cell stack may cause degraded performance, induce thermo-mechanical stresses, and be a source of reduced stack durability. The three-dimensional (3-D) model developed for this project includes coupled thermal/flow finite element analysis (FEA) of a multi-cell stack integrated with an electrochemical model to determine internal heat generation rates. Sensitivity and optimization algorithms were used to examine the design and derive the best choice of the design parameters. Initial results showed how classic design-of-experiment (DOE) techniques integrated with the model were used to define a response surface and perform sensitivity studies on heat generation rates, fluid flow, bipolar plate channel geometry, fluid properties, and plate thermal material properties. Probabilistic design methods were used to assess the robustness of the design in response to variations in load conditions. The thermal model was also used to develop an alternative coolant flow-path design that yields improved thermal performance. Results from this analysis were recently incorporated into the latest Plug Power coolant flow-path design. This paper presents an evaluation of the effect of variation on key design parameters such as coolant and gas flow rates and addresses uncertainty in material thermal properties.

Download Full-text

Heat and Mass Diffusion Including Shrinkage and Hygrothermal Stress during Drying of Holed Ceramics Bricks

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.312-315.971 ◽

2011 ◽

Vol 312-315 ◽

pp. 971-976 ◽

Cited By ~ 16

Author(s):

J. Barbosa da Silva ◽

G. Silva Almeida ◽

W.C.P. Barbosa de Lima ◽

Gelmires Araújo Neves ◽

Antônio Gilson Barbosa de Lima

Keyword(s):

Moisture Content ◽

Three Dimensional ◽

Average Moisture Content ◽

Stress Distributions ◽

Drying Process ◽

Convective Boundary ◽

Volume Method ◽

Hygrothermal Stress ◽

Thermo Physical Properties ◽

Good Agreement

The Aim of this Work Is to Present a Three-Dimensional Mathematical Modelling to Predict Heat and Mass Transport inside the Industrial Brick with Rectangular Holes during the Drying Including Shrinkage and Hygrothermalelastic Stress Analysis. the Numerical Solution of the Diffusion Equation, Being Used the Finite-Volume Method, Considering Constant Thermo-Physical Properties and Convective Boundary Conditions at the Surface of the Solid, it Is Presented and Analyzed. Results of the Temperature, Moisture Content and Stress Distributions, and Drying and Heating Kinetics Are Shown and Analyzed. Results of the Average Moisture Content and Surface Temperature of the Brick along the Drying Process Are Compared with Experimental Data (T = 80.0oC and RH = 4.6 %) and Good Agreement Was Obtained. it Was Verified that the Largest Temperature, Moisture Content and Stress Gradients Are Located in the Intern and External Vertexes of the Brick.

Download Full-text

APPLICATION OF A NEW HAMILTONIAN OF INTERACTION TO THREE-DIMENSIONAL STRUCTURES

International Journal of Modern Physics B ◽

10.1142/s0217979204024707 ◽

2004 ◽

Vol 18 (09) ◽

pp. 1351-1368

Author(s):

ANDREI DOLOCAN ◽

VOICU OCTAVIAN DOLOCAN ◽

VOICU DOLOCAN

Keyword(s):

Experimental Data ◽

Cohesive Energy ◽

Noble Gases ◽

Three Dimensional ◽

The Other ◽

Ionic Crystals ◽

Coupling Constant ◽

Good Agreement

Using a new Hamiltonian of interaction we have calculated the cohesive energy in three-dimensional structures. We have found the news dependences of this energy on the distance between the atoms. The obtained results are in a good agreement with experimental data in ionic, covalent and noble gases crystals. The coupling constant γ between the interacting field and the atoms is somewhat smaller than unity in ionic crystals and is some larger than unity in covalent and noble gases crystals. The formulae found by us are general and may be applied, also, to the other types of interactions, for example, gravitational interactions.

Download Full-text