3. Analyze three examples

3.1 Example 1 – Industrial laundry generating liquid effluent at 90°C and 2 bars (gray water loaded with detergent, dissolved grease, fibers, etc.).

In order to reduce energy consumption and comply with regulatory requirements, the operator has integrated a heat recovery unit to preheat tap water to 15°C, which is then fed into the cleaning process. Recoverable power depends on :

• of the thermal efficiency target (recovery rate) selected for the project; thus, an efficiency of 60% generates a city water heating of 60% x (90-15) = 45°C;

• fluid flow rates; thus, the recoverable power Prec is deduced from the city water flow rate according to the following expression: Prec (in kW) = 4.18 x flow rate (kg/s)...