Continuous Reactor - Heat Transfer Capacity

Heat Transfer Capacity

The rate of heat transfer within a reactor can be determined from the following relationship:

qx = U.A.

Where qx = the heat liberated or absorbed by the process (W)

U = the heat transfer coefficient of the heat exchanger (W.m-2.K-1)

A = the heat transfer area (m2)

Tp = process temperature (K)

Tj = jacket temperature (K)

From a reactor design perspective, heat transfer capacity is heavily influenced by channel size since this determines the heat transfer area per unit volume. Channel size can be categorised in various ways however in broadest terms, the categories are as follows:

Industrial batch reactors : 1 – 10 m2/m3 (depending on reactor capacity)

Laboratory batch reactors : 10 – 100 m2/m3 (depending on reactor capacity)

Continuous reactors (non micro) : 100 - 5,000 m2/m3 (depending on channel size)

Micro reactors : 5,000 - 50,000 m2/m3 (depending on channel size)

Small diameter channels have the advantage of high heat transfer capacity. Against this however they have lower flow capacity, higher pressure drop and an increased tendency to block. In many cases, the physical structure and fabrication techniques for micro reactors make cleaning and unblocking very difficult to achieve.