Abstract:Air-cooled heat exchangers are utilized in various industries to cool process fluids. To have a better heat transfer, fins are used in the structure of exchangers. In this study, a set of experiments were performed to investigate the improvement in the amount of heat transfer in an air-cooled heat exchanger. For this purpose, a real case study was conducted on air-coolers in a natural gas compressor station; afterward, the finned tubes were replaced by pulsating heat pipes (PHPs), and a different type of fluid… Show more
The heat transfer performance of oscillating heat pipe (OHP) depends on various parameters, and one such vital parameter is the wettability of its surface. In a conventional OHP (COHP), the wettability on all sections is uniform. In the present numerical study, a hybrid OHP having different wettability at different sections, that is an OHP with a hydrophilic evaporator and a superhydrophobic condenser, is proposed to recover larger quantities of low-grade waste heat (WH). The performance of the hybrid OHP is numerically investigated for different filling ratios (FRs) varying the range of 30%–90% and varying low-grade WH temperatures (WHT) between 320 K and 350 K, with water as the working fluid. Incorporation of a hydrophilic evaporator reduced the start-up time by 20%–80%, which is attributed to early onset of bubble nucleation. At the same time, the superhydrophobic condenser, owing to lower surface tension forces, increased the rate of condensation by promoting dropwise condensation, resulting in increased sensible and latent heat transfer in the hybrid OHP. Also, it was observed that the slug motion in hybrid OHP increased with an increase in low-grade WHT. The heat transfer performance of hybrid OHP increased with an increase of FR up to 80%, and thereafter the heat transfer performance is decreased. It was envisaged from the results that the heat transfer performance of the hybrid OHP is increased with increase in low-grade WHT. The highest mean heat transfer coefficient of 1270 W/m2-K is obtained in hybrid OHP at an FR of 80% and WHT of 350 K, which is 70.52% higher than COHP, indicating its suitability in low-grade WH recovery systems.
The heat transfer performance of oscillating heat pipe (OHP) depends on various parameters, and one such vital parameter is the wettability of its surface. In a conventional OHP (COHP), the wettability on all sections is uniform. In the present numerical study, a hybrid OHP having different wettability at different sections, that is an OHP with a hydrophilic evaporator and a superhydrophobic condenser, is proposed to recover larger quantities of low-grade waste heat (WH). The performance of the hybrid OHP is numerically investigated for different filling ratios (FRs) varying the range of 30%–90% and varying low-grade WH temperatures (WHT) between 320 K and 350 K, with water as the working fluid. Incorporation of a hydrophilic evaporator reduced the start-up time by 20%–80%, which is attributed to early onset of bubble nucleation. At the same time, the superhydrophobic condenser, owing to lower surface tension forces, increased the rate of condensation by promoting dropwise condensation, resulting in increased sensible and latent heat transfer in the hybrid OHP. Also, it was observed that the slug motion in hybrid OHP increased with an increase in low-grade WHT. The heat transfer performance of hybrid OHP increased with an increase of FR up to 80%, and thereafter the heat transfer performance is decreased. It was envisaged from the results that the heat transfer performance of the hybrid OHP is increased with increase in low-grade WHT. The highest mean heat transfer coefficient of 1270 W/m2-K is obtained in hybrid OHP at an FR of 80% and WHT of 350 K, which is 70.52% higher than COHP, indicating its suitability in low-grade WH recovery systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.