Numerical simulation of the thermal state of a flooded pipeline taking into account unsteadiness of the process of heat insulation saturation with moisture

Heat loss of heat pipelines in moisture conditions of thermal insulation

“…Maximum values of relative volume concentrations in wet fibroporous material C max st are shown in Table 2. An analysis of nonstationary processes of heat and mass transfer of the system under consideration allow us to make the inference about what time to steady-state condition is 2 · 10 4 s and for the diffusion problem -5 · 10 3 s. This accords well with results [6]. From analysis of results shown in Fig.…”

“…1) are listed in Table 2 and in Fig. 2. 01029-p. 3 Validity and reliability of the obtained results follow from tests of the methods for convergence and stability of solutions on multiple meshes, fulfillment of the energy balance conditions at boundaries of the calculation domain, and is also confirmed by comparison of the obtained results and the known experimental [2] and theoretical [1,5,6] data obtained by other authors. The relative calculation error in all versions of the numerical analysis did not exceed 0.5%, which is acceptable for investigations of thermal conditions of the system under consideration (Fig.…”

“…(11) was determined by Riedel-Plank-Miller method [7]. The thermophysical properties of insulation at saturation with moisture and steam were determined from the well-known expressions [6] and the effective coefficient of thermal conductivity ef -by the formula…”

“…The largest contribution to the change of thermal conditions makes a change of thermal conductivity of thermal barrier material in wetting conditions [1][2][3]. One more important factor is a moisture evaporation [4,5] and a mass transfer [6].…”

Heat loss of heat pipelines in insulation moisture conditions with the evaporation

“…(11) was determined by Riedel-Plank-Miller method [7]. The thermophysical properties of insulation at saturation with moisture and steam were determined from the well-known expressions [6] and the effective coefficient of thermal conductivity λ ef -by the formula 3 3 , ef w w st st…”