Relationship between pressure drop and heat transfer of developing and fully developed flow in smooth horizontal circular tubes in the laminar, transitional, quasi-turbulent and turbulent flow regimes

Abstract

Highlights• The flow regime boundaries were the same for heat transfer and pressure drop. • Friction factor correlations for developing and fully developed flow. • Average Nusselt number correlations for developing and fully developed flow. AbstractLimited work has been done specifically focussing on the relationship between pressure drop and heat transfer in the transitional flow regime. The purpose of this study was therefore to experimentally investigate and compare the pressure drop and heat transfer characteristics of developing and fully developed flow in smooth horizontal circular tubes in the laminar, transitional, quasi-turbulent and turbulent flow regimes. An experimental set-up was designed, built and validated against data from literature. A smooth circular test section with an inner diameter of 11.5 mm, and maximum length-to-diameter ratio of 872, was used.Pressure drop and heat transfer measurements were taken at Reynolds numbers between 500 and 10 000 at different heat fluxes. Water was used as the test fluid and the Prandtl number ranged between 3 and 7. A total of 364 mass flow rate measurements, 36 809 temperature measurements and 2 583 pressure drop measurements were taken. Pressure drop and heat transfer measurements were taken simultaneously and the relationship between pressure drop and heat transfer was determined. It was found that the Reynolds numbers at which transition started and ended was the same for the pressure drop and heat transfer results. Correlations were developed to determine the relationship between heat transfer and pressure drop, as well as the average Nusselt numbers, in the laminar, transitional, quasi-turbulent and turbulent flow regimes, for both developing and fully developed flow in mixed convection conditions. It was found that the relationship between heat transfer and pressure drop can be used as an additional criterion to distinguish the different flow regimes. Graphical abstract

Single-phase mixed convection of developing and fully developed flow in smooth horizontal circular tubes in the laminar and transitional flow regimes

“…This paper forms part of a bigger study and is complimentary to the papers published by Everts and Meyer [45][46][47]. This paper investigated mixed convection laminar flow, as well as the effect of free convection on the laminar-turbulent transition along the tube length.…”

“…The details of the pressure taps and measurements are given in Everts and Meyer [46]. 2) side of the test section.…”

“…This paper investigated mixed convection laminar flow, as well as the effect of free convection on the laminar-turbulent transition along the tube length. Everts and Meyer [45] investigated the heat transfer characteristics of developing and fully developed flow in the transitional flow regime, while the relationship between heat transfer and pressure drop in all flow regimes was investigated and quantified in Everts and Meyer [46]. The results of these papers were used to develop the flow regime maps, for not only fully developed flow but also developing flow, presented in Everts and Meyer [47].…”

“…and (33) using 495 experimental data points of this study. From this table it follows that both correlations performed very well and were able to predict 95% of the data within 10% and all the data Average laminar friction factors By making use of the Colburn Analogy[63], the relationship between friction factor (pressure drop) and Colburn j-factor (heat transfer) was used by Everts and Meyer[46] to obtain a correlation to calculate the friction factors as a function of Nusselt number and…”

Inlet tube spacing and protrusion inlet effects on multiple circular tubes in the laminar, transitional and turbulent flow regimes

“…A part of this work was reviewed by Meyer [17]. The works included smooth tubes [19][20][21][22][23][24][25][26] using a constant wall temperature as well as a constant heat flux boundary condition, a comparison of smooth tubes with enhanced tubes [20,21,27], and characteristics of transition when the fluids previously tested (water and glycol) are replaced with a nanofluid [28]. Hysteresis effects were also investigated [20,21] in which experiments were conducted in small increasing Reynolds number increments, starting in the laminar flow regime, increasing through the transitional flow regime into the turbulent flow regime.…”