Design of Indirect Heat Recovery Systems with Variable-Temperature Storage for Batch Plants

This article aims to propose an iterative method for designing an indirect heat recovery system including the associated variable-temperature storage in a batch plant. A recirculated heat transfer medium (HTM) is applied to absorb surplus heat load from hot process streams and temporarily reserved in storage tanks, where the accumulated energy is then released to later cold process streams by exchanging heat with HTM. This work is a direct extension of one recent article where the restraint of constant temperature for HTM in each storage tank is relaxed to magnify the heat recovery potential. The design problem is formulated as a mixed-integer nonlinear program (MINLP) based on proposed superstructures. A novel iterative solution strategy for setting the variable temperatures of HTM in storage is provided by linking the network optimization tool (a GAMS program) and the streams temperature simulation software (a MATLAB program). One numerical example is explored to demonstrate the applicability of the proposed indirect heat exchanger network design method for batch processes.