الفهرس Only 14 pages are availabe for public view
 |  | from | 85 |  |  |
| | | from | 85 | | |
Abstract
A two-dimensional theoretical model has been carried out to predict the performance and temperature distribution inside a tubular type heat exchanger associated with specified gas burner at different operating conditions.
The model was validated with experimental measurements. The outlet temperature of heated air predicted by the model has close agreement with the experimental results. In spite, the exhaust gases exit temperature is at acceptable deviation, but the total flue gases temperature drop across the heater is in good agreement with the measured one for all operating conditions.
As a case study, the effect of heated air and fuel mass flow rates variation on the heat exchanger performance was explored. The simulation results showed that, the maximum heat gained by the air is from the section that followed the fire tube directly (the second gas-pass with the first air-pass), which absorbs about 50 % of the total transferred heat. It is found that, the axial heat transfer through the tubes wall at the partition plate especially for the last gas-rows of tubes avoid the tubes and the partition plate from high thermal stresses due to the high temperature difference existed between the inlet and outlet air.
The model can be used for the prediction of the heat exchanger performance depending on the construction design as well as the partition plate position and the air passes number. While, the maximum tubes wall temperature for the two air passes apparatus is lower than that for an air heater constructed with one air pass, which makes the operation safer.