The demand for energy is increasing rapidly owing to the industrialization and high population growth. At the same time, the light oil reserves are decreasing day by day. The total crude oil resources are approximately 9-11 trillion barrels (bbls) in the world, among which more than 2/3 are heavy oil and bitumen. The challenge associated is how to explore these high viscosity and low API gravity oil from these formations. Thermal enhanced oil recovery is commercially applicable and efficient enhanced oil recovery technique. The demand of energy can be fulfilled by exploring heavy oil reservoirs. With this objective, an improved coupled numerical model was developed coupling heat transport and multiphase flow under non-isothermal conditions to understand the feasibility of thermal enhanced oil recovery in low permeability heavy oil reservoirs. The numerical model was validated with the work of Nakornthap and Evans. Three different injection velocity 5.88 × 10-6 m/s, 8.82 × 10-6 m/s and 11.76 × 10-6 m/s were utilized to understand and check the feasibility of higher injection rate in reservoir or real field scenario. Further, the impact of injection velocity on temperature field distribution and viscous dissipation were investigated. The temperature channeling was found at velocity 11.76 × 10-6 m/s. Viscous dissipation was found dominating near to the production well in all injection scenario which shows that the convection effect dominates over conduction near to the production well. The viscous dissipation at the injection velocity 11.76 × 10-6 caused sudden shock or fall behaviour between 250 m to 262 m from the injection well. From the present investigation, high viscous dissipation near to the production well causes significant temperature rise for high injection rates. This results in temperature channeling near the production well, which implies that proper planning is required for higher injection rates scenario to avoid the improper heating near the production well to maximize the production. The study can be extended to the cross-sectional heterogeneous reservoir to understand the impact of permeability distribution on the temperature, viscosity of oil, and displacement sweep efficiency. The present work provides an idea for the implementation of optimum injection rate and future development of hot water flooding in a petroleum reservoir.