Experimental studies on single-phase flow and heat transfer in a narrow rectangular channel

The state-of-the-art studies on single-phase flow and hear transfer in narrow rectangular channels shows some difference in terms of the agreement with the conventional theory. To further make clear this issue, the experimental studies on single-phase flow and heat transfer in a narrow rectangular channel with deioned water as test fluid was carried out. The narrow rectangular channel had the following dimensions: depth (e) = 2 mm, aspect ratio (e/b) = 0.05, length to diameter ratio (L/Dh) = 300, and mean wall relative roughness (ɛ/Dh) = 8.3 × 10−4. The experiments were performed with the channel oriented uprightly. The parameters that were varied during the experiments included the mass flow rate, inlet temperature and heat flux. on the measured temperatures, mass flow rates, pressure drops and heat fluxes, the isothermal and non-isothermal friction factors and the local and mean Nusselt numbers have been calculated. The correlations for the isothermal friction factors and the mean Nusselt numbers have been developed, and have a satisfactory agreement with the conventional theory. Based on the property ratio method, the correlations for non-isothermal friction factors have been proposed, but the new exponent (m) for modifying variable-property effect need to be developed.