Steady-State Thermal Properties of Rectangular Straw-Bales (RSB) for Building

Abstract

Abstract:Straw is an inevitable product of cereal production and is available in huge quantities in the world. In order to use straw-bales as a building material, the characteristic values of the thermal performances should be determined. To not lose the benefits of the cheapness and sustainability of the material, the characteristics must be determined with simple and inexpensive means and procedures. This research aims to implement tools and methods focused at the determination of the thermal properties of straw-bales. For this study, the guidelines dictated by ASTM and ISO were followed. A measurement system consisting of a Metering Chamber (MC) was realized. The MC was placed inside a Climate Chamber (CC). During the test, a known quantity of energy is introduced inside MC. When the steady-state is reached, all the energy put into MC passes through its walls in CC, where it is absorbed by the air-conditioner. A series of thermopiles detect the temperature of the surfaces of the measurement system and of the specimen. Determining the amount of energy transmitted by the various parts of MC and by the specimen, it is possible to apply Fourier's law to calculate the thermal conductivity of the specimen.

Thermal Conductivity of Straw Bales: Full Size Measurements Considering the Direction of the Heat Flow

“…The average values of Buildings 2017, 7, 11 3 of 15 the thermal conductivity at 10 • C were, respectively, 0.072 W/mK and 0.051 W/mK in parallel and perpendicular orientations. Conti [11] developed a thermal conductivity measurement system for straw bales that was also based on a steady-state method. The designed hot-box is mainly composed of a metering chamber and a heater inside a climate chamber.…”

A review of material properties and performance of straw bale as building material

“…The majority of these measurements [14][15][16][17][18][19][20][21][22][23][24] were determined in accordance with guarded hot plate method, based on ISO 8302:1991. The other two steady-state methods which have been used in the straw bale studies are measurement using heat flow meter apparatus [25] based on ISO 8301, and measurements using small hot box apparatus [26][27][28] based on EN-ISO 8990:1994 or ASTM C1363-19 [29]. Thermal conductivity can also be measured comparatively quicker using transient method, such as transient plane source method [30], transient line-source method [31] and other method using thermal probe for measurement [32], though a more complex analytical process needs to be applied compared to steady-state method.…”

“…2 indicates no significant deviation of thermal conductivity from different sources of straw, e.g. barley [20,21], wheat [15,16,18,26,28] or rice [14]. Overall, straw with fiber oriented perpendicular or random to heat flow showed lower thermal Fig.…”

“…2. Measured Thermal Conductivity vs Density based on studies from Marques [14], Reif [15], Costes [16], DIBt [17], Cascone [18], D'Alessandro [19], Vejeliene [20], Laborel-Préneron [21], Samuel [22], Munch-Andersen [23], Shea [25], Conti [26], Buratti [27], Cornaro [28], Christian [29], Langmans [33]. conductivity compared to those arranged parallel, as observed by Munch-Andersen and Andersen [23], Christian et al [29], Langsmans et al [33], Vė jelienė [34] and Douzane et al [35].…”

Application of a CFD Validated Model to Plan Fan Heater Position within Flour Mills during a Heat Treatment for Insect Pest Control

“…changes in the wall structure-e.g., by changing layers of the external wall-paying particular attention to the selection of appropriate insulation and its related thickness [2,[25][26][27]; -window shields by using thermal sheets to reflect thermal radiation produced by fan heaters.…”