Factors affecting the in situ measurement accuracy of the wall heat transfer coefficient using the heat flow meter method

Meng, Xi; Yan, Biao; Gao, Yawen; Wang, Jun; Zhang, Wei; Long, Enshen

doi:10.1016/j.enbuild.2014.11.005

Cited by 104 publications

(45 citation statements)

References 21 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The fundamental difference between Equations (1) and (5) is in the numerator of the equations: in Equation (1) it is necessary to measure the heat flux of the wall, so the result is subject to a possible disruption of the heat flux due to the use of the plate [32][33][34] and has a high level of uncertainty associated with its location [35][36][37], while in Equation (5) the necessary variable measurement is only carried out by temperature probes, reducing the error associated with the probes' location.…”

Section: Theorymentioning

confidence: 99%

“…The test described in ISO 6781 may be useful to determine the position of the mortar joints. According to the indications of Meng et al [37], when the mortar joints cannot be determined, probes must be mounted without being vertically or horizontally aligned. A fixed mastic can also be used to achieve good contact with the wall [31].…”

Section: Selecting and Installing The Equipmentmentioning

confidence: 99%

“…• Thermocouples measuring the internal surface temperature should be mounted with a space of 10 cm between them, as well as 20 mm away from the mortar joints of the pieces of brick of the internal side of the wall [31,37] at a height of 1.5 m above the floor [19]. The test described in ISO 6781 may be useful to determine the position of the mortar joints.…”

Section: Selecting and Installing The Equipmentmentioning

confidence: 99%

“…Cucumo et al [36] indicated that the location of the plate has an influence on the correct heat flux measurement. In this sense, Meng et al [37] established that the maximum error of the U-value due to the use of thermocouples can be up to 6%, while that caused by the use of a heat flux plate can reach up to 26%.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Determining the U-Value of Façades Using the Thermometric Method: Potentials and Limitations

et al. 2018

View full text Add to dashboard Cite

Abstract:The thermal transmittance of building envelopes determines to a large extent the energy demand of buildings. Thus, there is a keen interest in having methods which can precisely evaluate thermal transmittance. From a scientific point of view, this study analyses the viability of the application of the thermometric method (THM), one of the most used methods in Spain. For this purpose, the test method has been improved by determining the adequate test conditions, the selection and installation of equipment, data acquisition and post-processing, and the estimation of uncertainty. We analyse eight case studies in a Mediterranean climate (Csa) to determine the potentials and limitations of the method. The results show that the values obtained through THM are valid under winter environmental conditions with relative uncertainties between 6% and 13%, while difficulties to perform the test in optimal conditions, and therefore to obtain valid results in warmer seasons, are detected. In this regard, the case studies which obtained a greater number of observations by performing the filtrate conditions were able to obtain representative results. Furthermore, there are significant differences depending on the kind of equipment and probes used during the experimental campaign. Finally, in warm climate regions a data filtrate can be considered for observations of a temperature difference higher than 5 • C, obtaining valid results for the case studies, although the rise in the thermal gradient can guarantee a greater stability of data.

show abstract

Section: Theorymentioning

confidence: 99%

Section: Selecting and Installing The Equipmentmentioning

confidence: 99%

Section: Selecting and Installing The Equipmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Determining the U-Value of Façades Using the Thermometric Method: Potentials and Limitations

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Even if we strictly adhere to the approach described by the reference standards, the HFM method presents some uncertainties. It is evident that the calculated values could be affected from temperatures and heat-flux measurement: Meng et al [13] studied which factors affect the in situ measurement of U when the HFM method is applied. They found that thermocouples and heat flow meter locations, as well as pasting angle, size and shape of heat flow meter affect the measurement at different extent.…”

mentioning

confidence: 99%

Improved Thermal Transmittance Measurement with HFM Technique on Building Envelopes in the Mediterranean Area

Aversa

Donatelli

Piccoli³

et al. 2016

Selected Scientific Papers - Journal of Civil Engineering

View full text Add to dashboard Cite

Although the designed theoretical value of U can be derived from the thermal parameters of layers composing an opaque element, according to ISO 6946:2007, measurements are necessary to confirm the expected behaviour. Currently, the measurements of thermal transmittance based on Heat Flow Meter method (HFM) and according to standard ISO 9869-1:2014 are widely accepted. Anyway, some issues related to difficulties in measurements are present: the roughness of wall surfaces, the proper contact between the heat flow plate and the temperature probes with wall surfaces, undesired changes in weather conditions. This work presents the results obtained in thermal transmittance measurements with a modified HFM method, widely described in this paper. Differences between U-values obtained with the modified HFM method and theoretical ones were in the range 0.6 -6.5 %. Moreover, the modified HFM method provided a result closer to the theoretical one, when compared to that obtained with standard HFM method (discrepancy with theoretical value were 0.6% and 16.4%, respectively).

show abstract

Impact of nano‐enhanced phase change material on thermal performance of building envelope and energy consumption

Tunçbilek

Arıcı

Krajčík

et al. 2022

Intl J of Energy Research

View full text Add to dashboard Cite

Summary Using phase change material (PCM) in the building envelope can provide energy saving advantages by shaving peak heating and cooling loads. However, the poor thermal conductivity of PCMs limits their application and potential benefits because of inadequate heat storage/release rates. Increasing effective thermal conductivity by adding metal nanoparticles with high thermal conductivity to PCM (NPCM) could be a promising method to accelerate the phase change process, thereby exploiting latent heat more effectively. The potential impact of the utilization of NPCM technology has not yet been adequately explored for building external walls. This study aimed to reveal whether the dispersal of highly conductive nanoparticles in PCM in external building walls helps conserve energy or not. PCM enriched with aluminium oxide nanoparticles (Al2O3) with a content of 1, 2, and 3 vol% was used. The outputs showed that the nanoparticle addition decreased the energy‐saving performance of PCM since the reduction in the thermal resistance and latent heat capacity caused by the nanoparticles loading was more profound than the enhancement provided by the improvement of latent heat exploitation caused by the increased thermal conductivity. For example, heating energy saving was reduced by 0.6% when a 3‐cm PCM with 1 vol% Al2O3 was used instead of a pure PCM. The negative impact increased to 1.7% by increasing the nanoparticle concentration to 3 vol%. Thus, augmenting the thermal conductivity for higher latent heat activation by adding nanoparticles was not beneficial for building wall applications in a hot‐summer Mediterranean climate. Highlights Effect of nanoparticle‐enhanced PCM on building energy saving. PCM with Al2O3 content of 0, 1, 2, and 3 vol% embedded in external wall. Yearly energy saving of 20.7% was achieved with pure PCM in the wall. Adding 3 vol% Al2O3 to PCM reduced heating energy saving by 1.7%. Negative effect on energy saving increased with increasing nanoparticle concentration.

show abstract

Factors affecting the in situ measurement accuracy of the wall heat transfer coefficient using the heat flow meter method

Cited by 104 publications

References 21 publications

Determining the U-Value of Façades Using the Thermometric Method: Potentials and Limitations

Determining the U-Value of Façades Using the Thermometric Method: Potentials and Limitations

Improved Thermal Transmittance Measurement with HFM Technique on Building Envelopes in the Mediterranean Area

Impact of nano‐enhanced phase change material on thermal performance of building envelope and energy consumption

Contact Info

Product

Resources

About