Thermal properties of wood-based panels: specific heat determination

Abstract

Ensuring reliability of data on thermal properties of wood-based panels is important for manufacturing processes, especially when it is recommended to shorten the cooling phase and stack the panels in hot conditions. Prediction of the heat transfer during cooling phase and normal or hot stacking based on accurate data is essentially important for attaining panels of required properties. The thermal properties are also required when designing houses, especially low-energy or passive ones. Therefore, a water calorimeter was adequately designed and constructed to ensure improvement in the accuracy of the specific heat measurements. The calorimeter was used to determine the specific heat. The attained accuracy estimated by the relative error was significantly increased, and the error values were less than 2 % for all types of the investigated particleboard and OSB. In case of low-density fiberboard (LDF), the maximum value of the relative error did not exceed 4 %. It was also shown that high accuracy required for the specific heat measurements was achieved for experiments in which high-mass samples were used, in contrast to measurements for such samples in traditional DSC systems. The results for the specific heat were within the range from 1420 to 1450 J/kg K for LDF and all types of particleboard. The effect of the investigated material density on the specific heat was not found. The only exception was in case of OSB for which the specific heat was ca. 1550 J/kg K, and it was approximately 100 J/kg K higher when compared to other panels.

Thermal properties of wood-based panels: thermal conductivity identification with inverse modeling

“…The specific heat was firstly measured with a DSC system, and the obtained results were used for the inverse identification of the thermal conductivity as a function of temperature. The present study exploited the same methodology and the results of the specific heat measurements as reported by Czajkowski et al (2016) were used for determining the thermal conductivity with the inverse method. It was assumed that due to the space orientation of strands, particles or fibers in wood-based panels, the inplane thermal conductivities have to be similar and it was postulated in the present study to regard the in-plane values of the property as equal.…”

“…for a density of 660 kg/m 3 , specific heat of 1500 J/(kg K), and thermal conductivity equal to 0.12 W/(m K) as determined at a temperature of 20.3°C. The OSB thermal properties of the present study consisted of the following values: density of 619 kg/m 3 , specific heat of 1552 J/(kg K) as reported by Czajkowski et al (2016) and the identified in-plane and transverse thermal conductivity parameterized by Eq. (5) with coefficients given in Table 2.…”

“…The data were supplemented again by the set of properties obtained for PB1. The set consisted of a density of 634 kg/m 3 , specific heat of 1441 J/(kg K) as measured by Czajkowski et al (2016) and the identified in-plane and transverse thermal conductivity parameterized by Eq. (5) with coefficients given in Table 2.…”

“…It practically disparaged the data for predicting transient heat transfer in wood-based panels. The significant improvement of modeling was obtained when applying the measured values of specific heat (Czajkowski et al 2016) as well as identified values of the in-plane and transverse thermal conductivity.…”

“…Therefore, proper estimation of the specific heat and the thermal conductivity may be essential for increasing accuracy of predictions. The problem of the specific heat measurements of woodbased panels has already been discussed in a previous study and new results of the property have been delivered (Czajkowski et al 2016). Data describing the thermal conductivity, obtained 40 and 50 years ago (e.g.…”