scholarly journals Optimization method for prefabricated restroom envelope energy saving characteristics in hot summer and cold winter zone

2021 ◽  
pp. 014459872199393
Author(s):  
Lirui Zhang ◽  
Hong Zhang ◽  
Xu Xu ◽  
Ling Dong
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Energy Consumption ◽  
Transfer Coefficient ◽  
Thermal Characteristics ◽  
Optimization Method ◽  
Building Energy ◽  
Building Envelope ◽  
Cold Winter ◽  
Energy Consuming

In order to reduce the restroom envelope energy consumption, one optimization method on basis of analyzing the influence of heat transfer coefficient on the performance of a prefabricated restroom envelope in a hot summer and cold winter zone was proposed. An energy-consuming model of prefabricated restroom in Nanjing is initially built based on Designer's Simulation Toolkit software. Subsequently, the effect of external walls, rooftops, external windows with various thermal characteristics on the building envelope is analyzed respectively. Simultaneously, a method that only changes the heat transfer coefficient of the prefabricated restroom envelope while keeping other parameters unchanged is adopted. Results show that, for a prefabricated restroom, the optimal range of heat transfer coefficient of the external wall, rooftop, and external window in hot summer and cold winter zone is 0.199∼0.22, 0.16∼0.19, and 3.0∼3.1 W/(m2·K), respectively. When the window-to-wall ratio is less than 0.2, the priority of the wall heat transfer coefficient on building energy consumption is higher than that of the rooftop heat transfer coefficient, simultaneously, the rooftop heat transfer coefficient has priority higher than window heat transfer coefficient. Thus, it is of great significance to optimize the design of the prefabricated restroom envelope in a hot summer and cold winter zone, which provides relative reference for thermal performance improvement of prefabricated restrooms.

Energy Efficient Hybrid Nanofluids for Tubular Cooling Applications

2014 ◽  
Vol 592-594 ◽  
pp. 922-926 ◽  
Author(s):  
Devasenan Madhesh ◽  
S. Kalaiselvam
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Volume Concentration ◽  
Thermal Characteristics ◽  
Hybrid Nanofluid ◽  
Tubular Heat Exchanger ◽  
Overall Heat Transfer Coefficient ◽  
Flow Through ◽  
Hybrid Nanofluids

Analysis of heat transfer behaviour of hybrid nanofluid (HyNF) flow through the tubular heat exchanger was experimentally investigated. In this analysis the effects of thermal characteristics of forced convection, Nusselt number, Peclet number, and overall heat transfer coefficient were investigated.The nanofluid was prepared by dispersing the copper-titania hybrid nanocomposite (HyNC) in the water. The experiments were performed for various nanoparticle volume concentrations addition in the base fluid from the range of 0.1% to 1.0%. The experimental results show that the overall heat transfer coefficient was found to increases maximum by 30.4%, up to 0.7% volume concentration of HyNC.

scholarly journals Analysis of heat transfer coefficient of rammed earth wall in traditional houses in Vojvodina

2017 ◽  
Vol 21 (6 Part B) ◽  
pp. 2919-2930
Author(s):  
Vesna Lovec ◽  
Milica Jovanovic-Popovic ◽  
Branislav Zivkovic
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Characteristics ◽  
Rammed Earth ◽  
Single Family ◽  
Building Stock ◽  
Earth Structures ◽  
Rammed Earth Wall

Traditional Vojvodina house represents an important part of the building stock of the northern Serbian province of Vojvodina. The research examines the thermal transmittance of the walls of rammed earth, which is the basic structural and fa?ade element of traditional Vojvodina house, in two ways: by calculations in accordance with Serbian regulations and by measuring in situ. Parameters obtained from the measurements are compared with the calculated values for the three typical traditional Vojvodina rammed earth single family residential houses. The comparison between the values of the heat transfer coefficient, obtained by the calculation, and the results determined by in situ measurements show significant differences. It indicates that the thermal characteristics are better than calculated ones according to national regulations, but at the same time that, due to the complexity of the rammed earth walls and differences in the rammed earth structures, the results differ from case to case and can not be standardized.

scholarly journals Influence of airtightness of steel sandwich panel joints on heat losses

2020 ◽  
Vol 172 ◽  
pp. 05008
Author(s):  
Markus Kuhnhenne ◽  
Vitali Reger ◽  
Dominik Pyschny ◽  
Bernd Döring
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Building Envelope ◽  
The Finite Element Method ◽  
Transmission Losses ◽  
Building Envelopes ◽  
Metal Building ◽  
Effective Heat Transfer Coefficient ◽  
The Heat Transfer Coefficient

Energy saving ordinances requires that buildings must be designed in such a way that the heat transfer surface including the joints is permanently air impermeable. The prefabricated roof and wall panels in lightweight steel constructions are airtight in the area of the steel covering layers. The sealing of the panel joints contributes to fulfil the comprehensive requirements for an airtight building envelope. To improve the airtightness of steel sandwich panels, additional sealing tapes can be installed in the panel joint. The influence of these sealing tapes was evaluated by measurements carried out by the RWTH Aachen University - Sustainable Metal Building Envelopes. Different installation situations were evaluated by carrying out airtightness tests for different joint distances. In addition, the influence on the heat transfer coefficient was also evaluated using the Finite Element Method (FEM). The combination of obtained air volume flow and transmission losses enables to create an "effective heat transfer coefficient" due to transmission and infiltration. This summarizes both effects in one value and is particularly helpful for approximate calculations on energy efficiency.

scholarly journals Analysis of the Thermal Characteristics of a Composite Ceramic Product Filled with Phase Change Material

Buildings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 217 ◽  
Author(s):  
Joanna Krasoń ◽  
Przemysław Miąsik ◽  
Lech Lichołai ◽  
Bernardeta Dębska ◽  
Aleksander Starakiewicz
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Coefficient ◽  
Phase Change ◽  
Transfer Coefficient ◽  
Phase Change Material ◽  
Thermal Characteristics ◽  
Ceramic Product ◽  
Change Material ◽  
The Heat Transfer Coefficient

The article presents a comparative analysis carried out using three methods, determining the heat transfer coefficient U for a ceramic product modified with a phase change material (PCM). The purpose of the article is to determine the convergence of the resulting thermal characteristics, obtained using the experimental method, numerical simulation, and standard calculation method according to the requirements of PN-EN ISO 6946. The heat transfer coefficient is one of the basic parameters characterizing the thermal insulation of a building partition. Most often, for the thermal characteristics of the partition, we obtain from the manufacturer the value of the thermal conductivity coefficient λ for individual homogeneous materials or the heat transfer coefficient U for the finished (prefabricated) partition. In the case of a designed composite element modified with a phase change material or other material, it is not possible to obtain direct information on the above parameter. In such a case, one of the methods presented in this article should be used to determine the U factor. The U factor in all analyses was determined in stationary conditions. Research has shown a significant convergence of the resulting value of the heat transfer coefficient obtained by the assumed methods. Thanks to obtaining similar values, it is possible to continue tests of thermal characteristics of partitions by means of numerical simulation, limiting the number of experimental tests (due to the longer test time required) in assumed different partition configurations, in stationary and dynamic conditions.

scholarly journals Design of Flue Gas-Air Heat Exchanger for Regeneration of Desiccant System

2018 ◽  
Vol 225 ◽  
pp. 05006 ◽  
Author(s):  
Shaymaa H. Abdulmalek ◽  
Hussain H. Al-Kayiem ◽  
Aklilu T. Baheta ◽  
Ali A. Gitan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Waste Heat ◽  
Thermal Characteristics ◽  
Tube Diameter ◽  
Fuel Gas ◽  
Overall Heat Transfer Coefficient ◽  
Heat Exchanger Design

Heat recovering from biogas waste energy requires robust heat exchanger design. This paper presents the design of fuel gas-air heat exchanger (FGAHE) for recovering waste heat from biogas burning to regenerate desiccant material. Mathematical model was built to design the FGAHE based on logarithmic mean temperature difference (LMTD) and staggered tube bank heat transfer correlations. MATLAB code was developed to solve the algorithm based on overall heat transfer coefficient iteration technique. The effect on tube diameter on design and thermal characteristics of FGAHE is investigated. The results revealed that the smaller tube diameter leads to smaller heat transfer area and tube. On the other hand, the overall heat transfer coefficient and Nusselt numbers have larger rates at smaller tube diameter. In conclusion, the nominated tube diameter for FGAHE is the smaller diameter of 0.0127 m due to the high thermal performance.

scholarly journals Mechanical and Thermal Performance Characterisation of Compressed Earth Blocks

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2978 ◽  
Author(s):  
Elisabete R. Teixeira ◽  
Gilberto Machado ◽  
Adilson de P. Junior ◽  
Christiane Guarnier ◽  
Jorge Fernandes ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Compressive Strength ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Water Absorption ◽  
Thermal Performance ◽  
Pulse Velocity ◽  
Building Envelope ◽  
Compressed Earth Blocks ◽  
Earth Blocks

The present research is focused on an experimental investigation to evaluate the mechanical, durability, and thermal performance of compressed earth blocks (CEBs) produced in Portugal. CEBs were analysed in terms of electrical resistivity, ultrasonic pulse velocity, compressive strength, total water absorption, water absorption by capillarity, accelerated erosion test, and thermal transmittance evaluated in a guarded hotbox setup apparatus. Overall, the results showed that compressed earth blocks presented good mechanical and durability properties. Still, they had some issues in terms of porosity due to the particle size distribution of soil used for their production. The compressive strength value obtained was 9 MPa, which is considerably higher than the minimum requirements for compressed earth blocks. Moreover, they presented a heat transfer coefficient of 2.66 W/(m2·K). This heat transfer coefficient means that this type of masonry unit cannot be used in the building envelope without an additional thermal insulation layer but shows that they are suitable to be used in partition walls. Although CEBs have promising characteristics when compared to conventional bricks, results also showed that their proprieties could even be improved if optimisation of the soil mixture is implemented.

Determination of the Effect of Wall Heating Systems on Convective Heat Transfer Coefficient in Buildings

2014 ◽  
Vol 875-877 ◽  
pp. 1630-1636 ◽  
Author(s):  
Ozgen Acikgoz ◽  
Olcay Kincay ◽  
Zafer Utlu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Energy Consumption ◽  
Thermal Comfort ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Heated Wall ◽  
Real Size

Decreasing energy consumption and advancing thermal comfort are the most important aims of building engineering. Previously reported studies by many researchers have found that different usages of convective heat transfer coefficient (CHTC) correlations in heating system simulations have considerable impacts on calculated heating load in buildings. Hence, correct utilization of CHTCs in real size room enclosures has great importance for both energy consumption and thermal comfort. In this study, a modeled room was numerically heated from one vertical wall and cooled from the opposite wall in order to create a real room simulation. While cooled wall simulate heat losses of the room, heated wall simulates the heat source of enclosure. Effects of heated and cooled wall temperatures and characteristic length on CHTC and Nusselt number in the enclosure were numerically investigated for two (2-D) and three dimensional (3-D) modeling states. CHTCs and Nusselt numbers of a real size room with the dimensions of 6.00 by 2.85 by 6.00 were found with FLUENT CFD and graphics of change were drawn. As result, difference between 2-D and 3-D solutions was found approximately 10%. This was attributed as the effect of air flow pattern effects over other surfaces in the enclosure that can not be counted at 2-D solutions. The change of CHTC at different characteristic lengths was illustrated as well.

Thermal Characteristics of a Cylindrical Heat Pipe using Multi-Layer Screen Mesh Wick

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
R. Sankar Rao ◽  
S. Bhanu Prakash
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Heat Pipe ◽  
Thermal Characteristics ◽  
Wire Mesh ◽  
Working Fluid ◽  
Wick Structure ◽  
Screen Mesh

Heat pipe is the most widely used heat exchanging device in removal of heat from any given system at a faster rate. The thermal characteristics of heat pipe with single and multi-layered screen mesh wicks have been observed with two working fluids water and acetone. Heat pipe of length 250 mm and 12.7 mm outer diameter, made of copper material is used in all the trials of with and without wick structure. A 100 mesh stainless steel screen wire mesh is chosen as wick structure. Experiments were conducted at different heat loads and various inclinations with 100% fill ratio in evaporator. The performance is measured based on total thermal resistance and overall heat transfer coefficient. The heat pipe is found effective at 60o inclination with acetone as a working fluid and with four layered screen mesh wick. Uncertainty in thermal resistance and heat transfer coefficient is calculated for a heat input of 10W at 0 and 60 inclinations.

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