EFFICIENT HEAT TRANSFER FROM NON-CONDENSABLE GAS IN THE PROCESS OF MOIST EXHAUST HEAT RECOVERY

Most of the industrial waste heat is in the low temperature range. In the last few years, government agencies and equipment developers have paid attention to the advantages of heat recovery from moist industrial exhausts by cooling them to below the corresponding dew point temperature level. In case of non-aggressive and highly moisturized exhaust gas the recovery of vapor latent heat through efficient condensation can provide with significant energy savings. Indirect cooling condensers are it's the simplest solution for such heat recovery. However, low efficiency of those condensers makes the heat recovery economically not feasible. To develop a high efficient heat and mass exchanger it is necessary to investigate the combined transfer mechanisms from exhaust vapor and non-condensable portion of the exhaust to the heat transfer surface through the condensing water vapor. This paper describes main approaches to the description of this heat and mass transfer process, operating conditions for efficient gas cooling along with interaction between non-condensable gas and condensing vapor as well as considerations of influence of heat transfer surface on efficient condensation.