scholarly journals Analysis of heat transfer and factors affecting the thermal propertieson rib 1x1 knitwear

2021 ◽  
Vol 72 (04) ◽  
pp. 361-367
Author(s):  
MARIJA PEŠIĆ ◽  
VASILIJE PETROVIĆ ◽  
NENAD ĆIRKOVIĆ ◽  
JOVANA STEPANOVIĆ
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Thermal Resistance ◽  
Cotton Yarn ◽  
Knitted Fabrics ◽  
Clothing Insulation ◽  
Factors Affecting ◽  
Clothing Comfort ◽  
The One ◽  
The Impact

Clothing comfort is very important feature which is considered as a result of different process of heat exchange between human body, clothing and environment. The purpose of this paper is to analyse the impact of clothing insulation on the heat transfer. The measurements were carried out on commercially 1x1 RIB knitted fabrics used for the production of next-to-skin shirts. The one group of samples are made from 100% cotton yarn and another with 96% cotton and 4%lycra. It is noticed that knitted material composition affected the change in heat resistance. Also, this paper presents and verifies the correlation between the measured values of thermal resistance (Rct) and the knitwear thickness (dpl), the covering factor (K), the porosity of the twists (e) and the surface coefficient (dp). Based on these results, a mathematical model for calculating thermal resistance is proposed. Comparing the results obtained with the proposed equation and the measured results, we can see that the deviations are minimal. The highest deviation for sample C4 is 0.05%,while the largest deviation for sample CL4 is 4.6%.

Heat Transfer Analysis and Energy-Saving Methods of the Exterior Windows in the Northern Area

2014 ◽  
Vol 881-883 ◽  
pp. 1233-1236
Author(s):  
Zhong Hua Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Energy Saving ◽  
Outdoor Environment ◽  
Heat Transfer Analysis ◽  
Radiation Heat ◽  
Mathematical Formula ◽  
Factors Affecting ◽  
Northern Area ◽  
Indoor And Outdoor

In this paper, ways of heat transfer through windows and doors between the indoor and outdoor environment in the northern area are summarized. And every heat transfer way is described by mathematical formula. On this basis, methods to improve the energy saving performance of exterior windows are put forward according to factors affecting heat transfer through windows. The first method is increasing solar radiation heat, and then reducing heat loss by infiltration, and increasing the thermal resistance as much as possible. Ideal form of energy-saving window is proposed based on compared windows with different material and thermal resistance.

Location of a multinational corporation in a cluster

2016 ◽  
Vol 24 (2) ◽  
pp. 144-167 ◽  
Author(s):  
Dorota Leszczyńska ◽  
Erick Pruchnicki
Keyword(s):  
Mathematical Model ◽  
Knowledge Transfer ◽  
Tacit Knowledge ◽  
Mathematical Expression ◽  
Decision Criterion ◽  
Specific Knowledge ◽  
Content Type ◽  
The One ◽  
Effective Transfer ◽  
The Impact

Purpose A multinational company (MNC) looking to locate within a cluster is mainly interested in gaining access to scarce and highly valuable tacit knowledge. The transfer of such resources first requires sharing a certain degree of architectural and specific knowledge. This paper aims to examine the transfer of systemic technological expertise (specific tacit knowledge) that is incorporated into organisational practices (architectural knowledge). To quantify the level of knowledge transfer involved, the present study defines the architectural distance between the MNC and the cluster. Design/methodology/approach The mathematical expression of acquisition performance is inferred from a conceptual study that formulates hypotheses regarding the impact of these variables on knowledge transfer. The MNC chooses its location in such a way as to maximise this performance. Findings Applying a mathematical model to knowledge transfer between two of the MNC units helps to determine if the locally acquired knowledge could benefit other units of the MNC. Research limitations/implications The present study defines the architectural distance between the MNC and the cluster. This architectural distance is defined by a vector composed of social, organisational, cultural, institutional, technological and geographic distances between the new acquisition and its network of local partners, on the one hand, and the MNC, on the other. Knowledge transfer also depends on the business players’ trust and motivation. Further research through a quantitative study would be useful to improve the links between the proposed mathematical model and the efficiency of an MNC’s location within a cluster. Practical implications The solution to the optimisation problem allows to put forward a simple decision criterion to assist a manager who has to face the problem of an optimal location choice. Originality/value First, this study contributes to a better understanding of how knowledge transfer effects may interact with cluster effects, while explaining a subsidiary’s performance with regard to location. Second, it provides an interpretation of the concept of knowledge embeddedness by showing that the effective transfer of architectural and specific knowledge involves the prior sharing of a certain amount of this knowledge.

scholarly journals Impact of convection on thermographic analysis of silver based thermal joints

2020 ◽  
Vol 32 (4) ◽  
pp. 241-246
Author(s):  
Krzysztof Jakub Stojek ◽  
Jan Felba ◽  
Johann Nicolics ◽  
Dominik Wołczyński
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Energy Loss ◽  
Thermal Resistance ◽  
Analysis Method ◽  
Content Type ◽  
Heat Transfer Efficiency ◽  
Lowered Pressure ◽  
Thermographic Analysis ◽  
The Impact

Purpose This paper aims to develop thermal analysis method of thermal joints characterization. The impact on convection on thermal resistance analysis with use thermography for silver-based thermal joints were investigated for non-metallized and metalized semiconductor surfaces. Heat transfer efficiency depends on thermal conductivity; radiation was used to perform thermographic analysis; the convection is energy loss, so its removing might improve measurements accuracy. Design/methodology/approach Investigation of thermal joints analysis method was focused on determination of convection impact on thermal resistance thermographic analysis method. Measuring samples placed in vacuum chamber with lowered pressure requires transparent window for infrared radiation that is used for thermographic analysis. Impact of infrared window and convection on temperature measurements and thermal resistance were referred. Findings The results showed that the silicon window allowed to perform thermal analysis through, and the convection was heat transfer mode which create 15% energy loss. Originality/value It is possible to measure thermal resistance for silver-based thermal joints with convection eliminated to improve measurements accuracy.

Evaluating the effect of subsidies for rural development on agri-food and forestry firms

2019 ◽  
Vol 27 (80) ◽  
pp. 150-167
Author(s):  
José A. Pérez-Méndez ◽  
María Pérez-Urdiales ◽  
David Roibas
Keyword(s):  
Rural Development ◽  
Technical Efficiency ◽  
Technical Progress ◽  
Stochastic Frontier ◽  
Content Type ◽  
Factors Affecting ◽  
Forestry Industry ◽  
The One ◽  
The Impact ◽  
Positive Effect

Purpose This paper aims to evaluate the impact of the subsidies established by Measure 123 of the Rural Development Policy on the productivity of a sample of agri-food and forestry companies in the region of Asturias over the period 2006-2009. Design/methodology/approach The authors estimate a stochastic frontier function which allows subsidies to be considered as affecting both the level of technical efficiency and technical progress. Findings The results show that while subsidies have a positive effect on the technical progress of companies in the agri-food industry, for the forestry industry, the effect materializes as an improvement in technical efficiency. Additionally, other factors affecting either, technical progress and technical efficiency were identified. Originality/value This study adopts a model that allows the separate identification of the effect of subsidies on the level of efficiency, on the one hand, and on the technical progress, on the other.

scholarly journals A Simplified Technique for Thermal Analysis of a Fenestration system with a Venetian Blind

2021 ◽  
Author(s):  
Hidayat Ullah Shahid
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Approximate Model ◽  
Vertical Surface ◽  
Shading Devices ◽  
The One ◽  
The Impact ◽  
Venetian Blind

A simplified 1-D numerical model of a window and horizontal Venetian blind assembly has been developed. This model provides a realistic estimate of the advantage of using blinds to control the window heat gain or loss. The free convective heat transfer rate from an isothermal vertical surface adjacent to a set of horizontal louvres has been studied numerically. This configuration is an approximate model of an indoor window glazing with a Venetian-type blind. Knowledge of the effect of blinds on the free convection at the indoor window surface is important for understanding and predicting the impact of shading devices on the overall thermal performance of a window. The convective heat transfer results are used in the one-dimensional model of the complete fenestration system to study the effect on key performance parameters. The results show that louvred blinds can have a significant beneficial effect on window thermal performance.

scholarly journals Modeling of additive height and numerical analysis of cooling parameters for aero blade remanufacturing

2021 ◽  
Vol 12 (2) ◽  
pp. 803-818
Author(s):  
Miao Gong ◽  
Shijie Dai ◽  
Tao Wang ◽  
Liwen Wang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Numerical Analysis ◽  
Cooling Effect ◽  
Transfer Model ◽  
Factors Affecting ◽  
Coupled Heat Transfer ◽  
Blade Repair ◽  
Geometric Morphology ◽  
The Mathematical Model

Abstract. Additive remanufacturing height and matching cooling parameters are the key factors affecting blade repair quality. First, the mathematical model of the single additive remanufacturing repair height and wire-feeding speed was established, the solution method was proposed and the numerical solution was obtained, and the validity of the model was verified by experiments. Then, based on the calculation results of a single additive remanufacturing repair, the geometric morphology of the cross section under double additive remanufacturing repair was analyzed, and the mathematical model was established. Second, based on the optimal parameters obtained by numerical analysis and the mathematical model, the fluid structure coupling heat transfer model of “blade fixture” for base channel cooling was established. The cooling effect of the typical section under different initial temperatures and different flow rates was calculated, and the coupled heat transfer in the process of blade remanufacturing was explained by the mechanism. Third, through the comparative analysis of the cooling effect, optimal cooling parameters of double additive remanufacturing repair were obtained, and the model of coupled heat flow was verified by experiment. The results showed that the mathematical model of additive remanufacturing height is effective for studying the thermal cycle and cooling effect of welding, and the cooling parameters obtained by numerical analysis can effectively guarantee the quality of double additive remanufacturing of blade repair.

scholarly journals Use of fractional calculus in modeling of heat transfer process through external building partitions

2018 ◽  
pp. 61-70
Author(s):  
Ewa Szymanek
Keyword(s):  
Heat Transfer ◽  
Differential Equation ◽  
Mathematical Model ◽  
Heat Transfer Process ◽  
Heat Distribution ◽  
Experiment Data ◽  
Numerical Studies ◽  
External Conditions ◽  
Fractional Differential ◽  
The Impact

This paper is devoted to experimental and numerical studies of heat distribution in an external building bulkhead. It analyzes the variation of temperature across the width of the bulkheads including the impact of changing external conditions. Mathematical model used in the research is formulated based on a fractional differential equation, which was proven to be a useful tool for describing this type of process in previous paper. Numerical results are compared with experiment data for different bulkhead configurations.

scholarly journals A one-dimensional modeling study on the effect of advanced insulation coatings on internal combustion engine efficiency

2020 ◽  
pp. 146808742092158
Author(s):  
Alberto Broatch ◽  
Pablo Olmeda ◽  
Xandra Margot ◽  
Josep Gomez-Soriano
Keyword(s):  
Heat Transfer ◽  
Combustion Engine ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Insulation Material ◽  
One Dimensional ◽  
Engine Efficiency ◽  
Dimensional Modeling ◽  
The One ◽  
The Impact

This article presents a study of the impact on engine efficiency of the heat loss reduction due to in-cylinder coating insulation. A numerical methodology based on one-dimensional heat transfer model is developed. Since there is no analytic solution for engines, the one-dimensional model was validated with the results of a simple “equivalent” problem, and then applied to different engine boundary conditions. Later on, the analysis of the effect of different coating properties on the heat transfer using the simplified one-dimensional heat transfer model is performed. After that, the model is coupled with a complete virtual engine that includes both thermodynamic and thermal modeling. Next, the thermal flows across the cylinder parts coated with the insulation material (piston and cylinder head) are predicted and the effect of the coating on engine indicated efficiency is analyzed in detail. The results show the gain limits, in terms of engine efficiency, that may be obtained with advanced coating solutions.

Analysis of heat transfer characteristics in textiles and factors affecting thermal properties by modeling

2019 ◽  
Vol 89 (21-22) ◽  
pp. 4681-4690 ◽  
Author(s):  
Hua Shen ◽  
Kaifang Xie ◽  
Haoxuan Shi ◽  
Xiaofei Yan ◽  
Lexi Tu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Mass Density ◽  
Test Plate ◽  
Heterogeneous Model ◽  
Factors Affecting ◽  
Heat Leakage ◽  
Experiment And Simulation ◽  
The One ◽  
High Consistency

The heat transmission through a fabric during the measurement of thermal resistance was simulated by a novel heterogeneous model that was constructed according to the structure of ThermolabII Tester KES-F7. In this model, the heat transmissions along the longitudinal and transverse directions of yarn were treated independently. The material constants of fabrics, such as mass density, specific heat, thermal conductivity and thickness, were used as parameters for simulation in this fabric model. The validity of this model was then confirmed by the high consistency between the heat flux obtained from experiment and simulation, with the average difference ratio lower than 5%. The simulation results suggested that the guard area could effectively reduce the horizontal heat leakage from the test plate when the experimental fabric was thin. Only less than 8% of heat leaked in the one-layer case, while the leakage was significantly aggravated when more layers of fabric were stacked, resulting in the considerably lower thermal insulation achieved in both experiment and simulation compared with that in real fabrics. The temperature distribution in the model also implied that the longitudinal and transverse thermal conductivity of yarn exerted great effect on the heat leakage during the measurement. Moreover, for multilayers consisting of different fabrics, the laying sequence could obviously influence the heat leakage and, consequently, change the obtained thermal resistance.

Sign in / Sign up

Export Citation Format

Share Document