Passive House and Construction Standard: Example Design and Multi-Objective Optimization

2015 ◽  
Vol 719-720 ◽  
pp. 177-180
Author(s):  
Kağan Poyraz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cross Section ◽  
Thermal Insulation ◽  
Multi Objective Optimization ◽  
Passive House ◽  
Multi Objective ◽  
The Cross ◽  
Set Up

Due to environmental and energy matters, importance of future construction trend-Passive House Design is increasing all over the world. In Europe, already recommended values ​​for passive buildings are included in thermal insulation standards and energy regulation directives. There is a wide range of construction materials nowadays. The key point is using proper techniques by harmonizing correct practice and materials. In this regard, smart optimization set-up approach is necessary in order to achieve the most suitable design which has the lowest CO2 and SO2 values and appears as the cheapest option. The sample given in this paper is an example of an exterior wall design for residential passive houses (heat transfer coefficient (U) value through the cross section is 0,108 W/m²K). Connected with the aim of the paper, which is showing an multi-objective optimization method for choosing the best thermal insulation design in the case of that more than one projection, results of given example design in the paper is used. Simultaneously, criteria of total thickness, heat transfer coefficient (U) through the cross section, global warming potential (GWP), acid produce (AP), primary energy content (PEI) non renewable and cost in 2013 per m2 are included in “Smart optimization set-up approach diagram”.

scholarly journals Enhancement of Impingement Heat Transfer With the Crossflow Normal to Ribs and Pins Between Each Row of Holes

2018 ◽  
Author(s):  
Abubakar M. El-Jummah ◽  
Gordon E. Andrews ◽  
John E. J. Staggs
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Pressure Loss ◽  
Cross Flow ◽  
Experimental Results ◽  
Hole Density ◽  
Impingement Heat Transfer ◽  
The Cross ◽  
Flow Maldistribution

Impingement heat transfer investigations with obstacle (fins) on the target surface were carried out with the obstacles aligned normal to the cross-flow. Conjugate heat transfer (CHT) computational fluid dynamics (CFD) analysis were used for the geometries previously been investigated experimentally. A 10 × 10 row of impingement jet holes or hole density, n, of 4306 m−2 with ten rows of holes in the cross-flow direction was used. The impingement hole pitch X to diameter D, X/D, and gap Z to diameter, Z/D, ratios were kept constant at 4.66 and 3.06 for X, D and Z of 15.24, 3.27 and 10.00 mm, respectively. Nimonic 75 test walls were used with a thickness of 6.35 mm. Two different shaped obstacles of the same flow blockage were investigated: a continuous rectangular ribbed wall of 4.5 mm height, H, and 3.0 mm thick and 8 mm high rectangular pin-fins that were 8.6 mm wide and 3.0 mm thick. The obstacles were equally spaced on the centre-line between each row of impingement jets and aligned normal to the cross-flow. The two obstacles had height to diameter ratios, H/D, of 1.38 and 2.45, respectively. Comparison of the predictions and experimental results were made for the flow pressure loss, ΔP/P, and the surface average heat transfer coefficient (HTC), h. The computations were carried out for air coolant mass flux, G, of 1.08, 1.48 and 1.94 kg/sm2bar. The pressure loss and surface average HTC for all the predicted G showed reasonable agreement with the experimental results, but the predictions for surface averaged h were below the measured values by 5–10%. The predictions showed that the main effect of the ribs and pins was to increase the pressure loss, which led to an increased flow maldistribution between the ten rows of holes. This led to lower heat transfer over the first 5 holes and higher heat transfer over the last 3 holes and the net result was little benefit of either obstacle relative to a smooth wall. The results were significantly worse than the same obstacles aligned for co-flow, where the flow maldistribution changes were lower and there was a net benefit of the obstacles on the surface averaged heat transfer coefficient.

scholarly journals Point thermal bridges of insulated pitched roof structures

2018 ◽  
Vol 146 ◽  
pp. 03014 ◽  
Author(s):  
Jiří Šál ◽  
Daniela Štroufová ◽  
Petra Bednářová
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Insulation ◽  
Overall Heat Transfer Coefficient ◽  
Building Insulation ◽  
Insulation Systems ◽  
Thermal Bridges ◽  
The Individual ◽  
The Heat Transfer Coefficient

The current demands on building insulation are continuously increasing. It is understood that the lower the heat transfer coefficient of a particular part of a construction is, the greater the importance of systemic thermal bridges. This article compares the individual systems of insulation of pitched roofs in terms of the heat transfer coefficient. The focus is on the size of the point thermal bridges in rafter thermal insulation systems and determines their impact on increasing the overall heat transfer coefficient. However, it should be noted that point thermal bridges are individually very small and combined only contribute to 2% of the overall heat transfer coefficient of parts of a structure.

Analysis of Thermal – Moisture Problems in Massive Wooden Sandwich Structures

2016 ◽  
Vol 824 ◽  
pp. 563-570
Author(s):  
Jakub Dohnal ◽  
Jan Pěnčík
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Water Vapor ◽  
Transfer Coefficient ◽  
Thermal Insulation ◽  
Sandwich Structure ◽  
Sandwich Structures ◽  
Different Thickness ◽  
Reducing Capacity ◽  
Interior Side

This article focuses on hygrothermal problems in massive wooden sandwich structures. Wood in sandwich structures is already artificially dried before processing, and therefore does not further shrink, as it does in the case of log cabins. Analysed sandwich structure is composed from three layers, and is formed of wooden beam in interior side, thermal insulation and wooden beam in the exterior side. The composition of analysed structure is considered in different thickness with respect to the required heat transfer coefficient. Massive wooden beam on the exterior side causes troubles which exhibits in the reducing capacity of diffusion of water vapor. It is therefore possible that water vapor condenses on the interface of wood and the thermal insulation under certain boundary conditions. Therefore, it is appropriate to place massive wooden beam closest to the interior side. This solution would improve the balance of the diffusion permeability to water vapor permeating from the interior side to the exterior side.

Termorenowacja stolarki okiennej

BUILDER ◽  
2019 ◽  
Vol 261 (4) ◽  
pp. 118-122
Author(s):  
Romana Antczak - Jarząbska ◽  
Maciej Niedostakiewicz
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Insulation ◽  
The State ◽  
Before And After ◽  
The Heat Transfer Coefficient

The paper presents the results of preliminary calculations of the heat transfer coefficient for historic windows made for the state before and after their renovation. The aim of the analysis was to obtain the values of thermal insulation parameters demanded by the regulations, while not losing the historical value of the window. The described example of the thermo-renovation concept of the existing window consisted in installing an additional window panel from the inside.

scholarly journals Local Heat Transfer Analysis in a Single Microchannel with Boiling DI-Water and Correlations with Impedance Local Sensors

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6473
Author(s):  
Mohammadmahdi Talebi ◽  
Sahba Sadir ◽  
Manfred Kraut ◽  
Roland Dittmeyer ◽  
Peter Woias
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cross Section ◽  
Flow Boiling ◽  
Rectangular Cross Section ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Experimental Conditions ◽  
Impedance Measurements

Determination of local heat transfer coefficient at the interface of channel wall and fluid was the main goal of this experimental study in microchannel flow boiling domain. Flow boiling heat transfer to DI-water in a single microchannel with a rectangular cross section was experimentally investigated. The rectangular cross section dimensions of the experimented microchannel were 1050 μm × 500 μm and 1500 μm × 500 μm. Experiments under conditions of boiling were performed in a test setup, which allows the optical and local impedance measurements of the fluids by mass fluxes of 22.1 kg·m−2·s−1 to 118.8 kg·m−2·s−1 and heat fluxes in the range of 14.7 kW·m−2 to 116.54 kW·m−2. The effect of the mass flux, heat flux, and flow pattern on flow boiling local heat transfer coefficient and pressure drop were investigated. Experimental data compared to existing correlations indicated no single correlation of good predictive value. This was concluded to be the case due to the instability of flow conditions on one hand and the variation of the flow regimes over the experimental conditions on the other hand. The results from the local impedance measurements in correlation to the optical measurements shows the flow regime variation at the experimental conditions. From these measurements, useful parameters for use in models on boiling like the 3-zone model were shown. It was shown that the sensing method can shed a precise light on unknown features locally in slug flow such as residence time of each phases, bubble frequency, and duty cycle.

Design Optimization of Networks of Cooling Passages

2005 ◽  
Author(s):  
Nenad Jelisavcic ◽  
Thomas J. Martin ◽  
Ramon J. Moral ◽  
Debasis Sahoo ◽  
George S. Dulikravich ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Coolant Flow ◽  
Flow Rates ◽  
One Dimensional ◽  
Multi Objective ◽  
Internally Cooled

A one-dimensional thermo-fluid flow network analysis program COOLNET was developed to predict coolant flow rates, total coolant pressures, bulk coolant total temperatures, and internal heat transfer coefficient distributions, inside internally cooled objects. The coolant passages were allowed to be an arbitrary network of one-dimensional fluid elements or tubes. Geometric parameters of each passage were optimized using a hybrid multi-objective optimization algorithm. For the chosen Pratt & Whitney gas turbine the cross-sectional areas, hydraulic diameters, ribs’ heights and angles in each passage were optimized in order to minimize coolant flow rate, coolant total pressure loss, and total heat removed by coolant from the system. Validation of the hybrid multi-objective optimizer was performed with various test functions. Also, validation of the COOLNET was done with existing Pratt & Whitney gas turbine blade. Program OBJ was written to connect hybrid multi-objective optimizer and COOLNET. Optimization process was visualized using Tecplot (commercial software). Program PLOT was written to write input file for Tecplot, purpose of PLOT was to visualize initial and optimized results. Analysis for the best optimal result is given. The resulting COOLNET analysis provided coolant flow rates, total and static pressures and temperatures, and the heat transfer coefficient of each fluid element. The COOLNET analysis algorithm would typically converge in 50 iterations requiring about 5 seconds of CPU time on a 3.0 GHz processor. Results demonstrated that in case of an internally cooled gas turbine blade an improvement in overall performance is possible. A typical design optimization required between 500-1,000 iterations with a population of 30 designs. Thus, total number of configurations analyzed was approximately 15,000-30,000.

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