Tube-Tube Heat Exchanger (TT_HE)
This novel vented double wall Tube- Tube Heat Exchanger (Rane and Tandale, 2002) enables exchange of heat between multiple streams. Concern of accidental mixing of the fluids exchanging heat is put to rest with this versatile and reliable heat exchanger. A tube-tube heat exchanger (TT_HE) is a double wall tubular heat exchanger wherein two or more tubes are placed side-by-side and bonded thermally using thermal bonding material (TBM) for effective transfer of heat. Use of bends and straight lengths in tube-tube heat exchanger results in significant enhancement in heat transfer due to secondary flows induced in the bends. The secondary flows induced in bend leads to heat transfer enhancement in bend as well as in straight length downstream of bend without significant increase in pressure drop.

Tubes are placed side-by-side in the TT_HE. Hence, diameter of tube replacing the outer tube of a tube-in-tube heat exchanger can be smaller. Tube diameter and number of tubes on each side can be chosen independent of each other, eg. 1-1, 2-1, n-n or n+1-n configurations are possible (Figure 1), resulting in greater flexibility in design. Figure 1: Sectional view of three TT_HE configurations