Gas-solid flows in pipes are common in industrial applications, such as pneumatic conveying, fluidized beds, pulverized coal combustion, spray drying and cooling, etc. The prediction of the pressure drop is essential in design of the systems, while the addition of granular particles to the gas flow causes an enhancement of heat transfer from the heated wall to the bulk fluid. The fully developed and overall pressure drop and overall heat transfer prediction in gas-solid flows in horizontal pipes have been investigated numerically using the Eulerian-Eulerian (E-E) approach, accounting for four-way coupling. For the prediction of fully developed pressure drop, fine particles (fly ash of size 20 to 150 μm) with the solid volume fractions of up to 0.1 have been considered. For the prediction of overall pressure drop and heat transfer, fine particles (flyash of size 30 to 50 μm) have been used in the simulations.