1st and 2nd Law Characteristics in a Micropipe: Integrated Effects of Surface Roughness, Heat Flux and Reynolds Number

Combined Effects of Pipe Diameter, Reynolds Number and Wall Heat Flux and on Flow, Heat Transfer and Second-Law Characteristics of Laminar-Transitional Micro-Pipe Flows

“…As the considered micro-pipe diameter range is consistent with the microchannel definition of Obot [16] (d ≤ 1.00 mm), the imposed wall heat flux values are decided in conjunction with the Reynolds number and the accompanying mass flow rate ranges, to bring about applicable and rational heating. The fixed parameters of the analyses are the length of the micro-pipe (L = 0.5 m), inlet temperature (T in = 278 K) and exit pressure (P ex = 0 Pa) of water and the non-dimensional surface roughness (ε * = 0.001), which is in harmony with those of Engin et al [8] (ε * ≤ 0.08), Sahin et al [19] (ε * ≤ 0.25), Ozalp [33][34][35] (ε * = 0.001-0.05) and…”

“…The influences of surface roughness and surface heat flux conditions, over the meshing intervals of the flow domain, are coupled by Direct Simulation Monte Carlo (DSMC) method. The author previously applied DMSC to compressible nozzle flow problems [21,22] and to micro-pipe flow scenarios with surface roughness [33][34][35]. The concept of triple transport conservation is as well incorporated into the DSMC, which makes it possible to sensitively evaluate the balance of heat swept from the micro-pipe walls, the energy transferred in the flow direction and also to perform accurate simulation for inlet/exit pressure boundaries.…”

“…The author employed the present computational method in his former work [22,[33][34][35] and detailed the essentials and the sub-steps of the procedure extensively. Thus, here only the fundamental issues of the methodological structure are defined.…”

“…As the available literature designates, real-time operational and structural parameter ranges in micro-pipe flows are broad, which as a consequence significantly promotes the possible process and output scenarios due to the individual and combined parameter influences. Recently, Ozalp [33][34][35] computationally investigated the momentum transfer, heat transfer and second-law characteristics of air flow in a circular micro-pipe with a diameter of d = 1 mm. The analyses were carried out in the Reynolds number and non-dimensional surface roughness ranges of Re = 1-2,000, ε * = 0.001-0.05.…”

Compressibility and rarefaction effects on entropy and entropy generation in micro/nano Couette flow using DSMC

“…He concludes that the cross-sectional total entropy generation is computed to be most influenced by pipe diameter at high wall heat flux and low Reynolds numbers. Ozlap [24] also studied the integrated effects of surface roughness, heat flux, and Reynolds number on the first and second law characteristics of laminar-transitional flow in a micropipe and showed that the frictional entropy is minor and the major portion of the total entropy generation is thermal based. Chigullapalli et al [25] formulated and applied a discrete version of the Boltzmann's H-theorem for analysis of nonequilibrium onset and accuracy of the numerical modelling of rarefied gas flows.…”