Reduced linear state model of hollow blocks walls, validation using hot box measurements

Coupled heat transfers in a three cavity hollow block subjected to an incident solar flux: Effect of heat conductivity

“…This block has good thermal insulation, lightweight, acoustic insulation etc. (Zhang et al [1], Gao et al [2]). But, in general, the heat transfer in the hollow block as the main unit of this envelope is complex and coupled by conduction in solid partitions, natural convection inside the cavities and radiation between the internal surfaces of the cavities.…”

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

“…The guided hot box method and the calibrated hot box method are often used to the wall's U-value in the lab and have the high measurement accuracy, but they do not suit to the in situ measurement due to the heavy measurement equipments or the complex in situ environments [18][19][20]. However, the heat flow meter method is most widely applied to measure U-values in situ due to the simplicity of the test equipment and system, but there remain concerns about the low measurement accuracy [21,22].…”

Inside Surface Temperature Evaluation of Hollow Blocks Wall by Reduced Linear State Model

“…Each one of the state variables in the resulting equivalent model has the same degree of controllability and observability. In other words, the idea for balancing technique is to find a realization to the reduction model, which corresponding observability and controllability gramians are equal and diagonal: Wc=Wo=Σ=diag(ω1, ω2, ...., ωn), where ω1≥ ω2≥... ≥ ωn>0 are the so-called Hankel singular [10] values and are the square roots of the eigenvalues of the product WcWo. In a balancing model, the state components corresponding to small Hankel singular values require much energy to be reached, while at the same time producing little energy on the output.…”

“…Considering rectangular mesh discretization, the arc part and cone-shaped part are simplified as rectangle just like shown in Fig.1 Fig . 1 Plan view, cross section and discretization of hollow block Before numerical simulation, air layer equivalent thermal conductivity is determined by numerical simulation [10] . Consequently, the air layer equivalent thermal conductivity (λ eq ) of hollow blocks, is taken as 0.28 W/m 2 K within our numerical model.…”