A. Specification of example

To illustrate the design of a shell-and-tube heat exchanger with twisted tubes, a case is presented for a heat exchanger system for wine liquor cooling in a wine production plant with a throughput 2,000 litres per hour. In this heat exchange system, countercurrent flow of the hot and cold streams is used; thus the wine liquor flows inside the tubes and the cooling medium (a 21% aqueous solution of calcium chloride, “CaCl₂ brine”) flows in the space between the tubes. The temperature of the CaCl₂ brine at the heat exchanger inlet is -6 ± 2 °C. The wine liquor enters the heat exchanger with a temperature +12 ± 2 °C and has to be cooled down to -2 ± 1 °C. The pressure drop has to be less than 5 × 10⁴ Pa. To facilitate cleaning, a modular design was selected for the system. Thus, a system consisting of 8 modules, connected by branch pipes, allowing one or more of the modules to be disconnected and cleaned whilst the other modules remained in operation. The modules are mounted on a frame and each module consists of a shell containing a bundle of 7 oval twisted tubes fastened into tube plates. Mutual contact between the twisted tubes (see Figure 386.1) ensures suppression of tube vibration (Dzyubenko, 1980 [1]).

(a) Calculation method

The total surface areas for heat transfer is defined as