In forced convection, which factors are crucial for determining heat transfer rate?

In forced convection, the crucial factors determining the heat transfer rate include fluid velocity and the temperature difference. The fluid velocity influences how quickly the fluid can carry heat away from or towards a surface. Higher velocities typically enhance the convective heat transfer coefficient, leading to increased heat transfer rates. The temperature difference between the solid surface and the moving fluid is equally important, as it drives the heat transfer process; larger temperature differences result in greater thermal energy transfer.

While other options mention various factors like ambient pressure and density, they do not directly influence the heat transfer rate in the context of forced convection to the same extent as fluid velocity and temperature difference do. Viscosity and surface area are significant but do not individually highlight how the forces of convection operate in a dynamic flow situation as directly as velocity and temperature difference do. Understanding these two key factors helps clarify how heat transfer is effectively managed in systems involving forced convection.