HEAT TRANSFER OF GAS-SOLID TWO-PHASE FLOWS IN A NOVEL SYSTEM FOR NON-PERIODIC ADSORPTION ENAHNCED CHEMICAL REACTION PROCESSES

Packed beds are widely used in the chemical and process industries where heat transfer plays a crucial role in determining the performance. Extensive investigations have been carried on the heat transfer behaviour of single phase gas flow through packed beds, gas-solid suspensions through ducts and pipes, and gas-solid flow in fluidized beds. However little information is directly relevant to the gas-solid suspension through a packed bed. This work introduces the concept of non-periodic adsorption enhanced reaction and reports a systematic experimental investigation of gas-solid two-phase mixtures flowing through a packed bed; the single phase gas flow behaviour is also obtained that acts as a comparison basis. Temperature profile inside the packed bed and wall temperature distributions are acquired through 28 type J thermocouples. The overall convective heat transfer coefficient is derived from the Logarithmic Mean Temperature Difference (LMTD) method. The influence of particle loading ratio and gas Reynolds number is investigated and compared with that of a single phase gas flow. The results show that gas-solid suspension can greatly enhance the overall heat transfer. The enhancement is a strong function of solids loading ratio but independent of the Reynolds number. Systematic temperature measurements reveal the complex heat transfer processes in the interior of the beds, which provides the insights into the kinetic chemical reactions and adsorption process.