Pressure loss and performance assessment of horizontal spiral coil inserted pipes during forced convective evaporation of R-600a

Abstract

Pressure loss and performance assessment of horizontal spiral coil inserted pipes during forced convective evaporation of R-600a. International Journal of Refrigeration.

Condensation heat transfer and pressure drop characteristics of Isobutane in horizontal channels with twisted tape inserts

“…By augmenting the refrigerant mass velocity from 119 to 264 kgm -2 s -1 , the impact of twisted tapes fades as the impacts of the flow velocity and the momentum pressure drops are much considerable. These results approve the studies of Naulboonrueng et al [38] and Alimardani et al [28] who stated that effects of using modified surfaces and inserts at lower mass velocities on the pressure drop increment is much considerable. However, the pressure drops increase by increment of mass velocity beyond 264 kgm -2 s -1 .…”

“…Therefore, it can be concluded that at higher mass velocities, the HTC enhancement can overweight the pressure drop increment resulting in performance factors higher than one. Previous studies also approve the current conclusions [28,38]. On the other hand, by augmenting the mass velocity beyond the optimum value the pressure drops and PF slightly decrease because the impacts of shear stresses between the fluid and frictional surfaces become stronger.…”

“…Within another experimental study on evaporation of R600a in horizontally placed pipes, Yang et al [27] reported that the refrigerant mass velocity and applied heat flux have significant impacts on the transitions of flow regimes from intermittent to annular; and the transition was experienced at a lower vapor quality with the increment of the mass velocity and applied heat flux. Within two other studies, Alimardani et al [28,29] explored flow boiling R600a in heat exchangers with coiled wire inserts under different refrigerant mass velocities ranged between 109.2 to 505 kgm -2 s -1 . Their studies showed that using wire coil inserts contributes to the enhancement of heat transfer, but a considerable growth in frictional pressure drop was also observed.…”

Flow pattern maps, pressure drop and performance assessment of horizontal tubes with coiled wire inserts during condensation of R-600a

“…Indeed, as it was discussed in previous studies [29,30], the volume of vapor refrigerant augments by increasing the vapor quality resulting in the vapor velocity larger than that of the liquid refrigerant film. Consequently, the larger velocity difference between two phases results in higher shear stress and therefore higher pressure losses.…”

Modelo numérico de detección de fugas para sistema de tuberias.

“…En el cálculo de las pérdidas de carga en tuberías desempeña un papel discriminante que el régimen de corriente sea laminar o turbulento [33]. El régimen de flujo depende principalmente de la razón de fuerzas inerciales a fuerzas viscosas en el fluido, conocida como número de Reynolds (NR) [34].…”