2. From minimum energy requirement to minimum exergy requirement

The construction of composite curves and the large composite curve allows the process to be studied and the minimum energy required to be identified. The utilities needed to meet the residual heating and cooling requirements must then be selected and sized.

All heating and cooling requirements for industrial processes are met by hot utilities (boilers, cogenerators, heat pumps, etc.) and cold utilities (cooling towers, refrigeration units, etc.), respectively.

The total operating cost of utilities certainly depends on the technologies chosen, but also on the temperature levels of the thermal energy delivered to meet the process requirements. Generally, the greater the difference between the process temperature and the utility temperature, the more exergy is destroyed