Enhancement of heat transfer through shell and tube exchangers stills taking high attention by researchers. The present work investigated the effect of shell diameter and tube length on heat transfer coefficient and pressure drop for shell side with both triangular and square pitches. In addition, the effect of baffle spacing and cutting space on heat transfer coefficient and pressure drop were studied. Moreover, standards fouling rates used for both shell and tube sides to estimate the reduced heat transfer. Increasing shell diameter with a triangular pitch and pull-through floating head recorded 3% increasing in heat transfer coefficient for only 0,05 m increasing in shell diameter. While 2.8% increase in heat transfer coefficient for shell side by 0.05 m increasing in shell diameter with split-ring floating head and square pitch. Heat transfer coefficient for shell side reduced by 15.15% by increasing baffle space by 0.2 from shell diameter and the pressure drop by 41.25%. Increasing cutting space from 15% to 25% decreases heat transfer coefficient by 5.56% and the pressure drop diminished by 26.3%. Increasing tube length by 0.61 m leads to enhance the heat transfer coefficient by 31.9% and pressure drop by 14.11% for tube side. For shell side, increasing tube length by 0.61 m gives 2.2% increasing in heat transfer coefficient and 21.9% increasing for pressure drop. Fouling resistance change on shell side shows a high effect on heat transfer more than same rate change on the tube side. Based on the result, this study can help designers to quick understand of each parameter effect on heat transfer into shell and tube exchangers.