Enhanced heat transfer of variable pitch helical baffle plate orifice plate-type heater for downhole in situ oil shale extraction.

This article focuses on the numerical simulation and performance analysis of a variable pitch helical baffle plate orifice plate-type heater designed to enhance heat transfer efficiency. Using Fluent software and the RNG k-ε turbulence model, the study investigates how different decreasing pitch intervals (Δx) of the helical baffle affect the heat transfer coefficient (h), average wall temperature (T̄), and temperature difference (ΔT) on the heating plates. Results show that increasing Δx reduces the average wall temperature and temperature difference, improving heat transfer uniformity and potentially extending heater lifespan; however, the comprehensive performance index h/ΔP¹ᐟ³ (heat transfer coefficient over pressure drop to the one-third power) peaks at Δx = 5 mm, indicating an optimal balance between heat transfer and pressure drop. The study also addresses localized overheating near the outlet by adding a straight folding plate to ensure uniform gas flow through the heating plates. These findings contribute to optimizing heater design for applications such as in situ oil shale extraction, aiming to improve efficiency and durability without causing environmental damage.