#Number of tubes in heat exchanger update

This work presents a novel algorithm for finding optimal detailed heat exchanger designs that can operate over multiple operational periods. These formulations are difficult to converge due to the large numbers of integer variables and nonconvex equations, have only been demonstrated on single shell exchangers, and have yet to be extended to multi-period heat exchanger designs. and continuous variables for velocities, heat transfer coefficients, heat exchanger areas, number of tubes, number of tube passes etc. Optimization approaches to the design of individual heat exchangers have typically involved the formulation of a large non-convex MINLP with integer variables for tube and shell-side stream allocations, number of baffles, baffle cuts, tube diameters, etc. The heuristics-based method used to design the individual exchangers was done manually and therefore the obtained designs are unlikely to be optimal, especially considering the multi-variable nature of the problem.

#Number of tubes in heat exchanger update

These designs were then used to update MINLP model via correction factors in order to converge to the same solution as the detailed designs. Thereafter, detailed shell-and-tube heat exchangers are designed using heuristics to obtain designs that are feasible across all periods of operation. (2016) presented a 2-step multi-period HEN synthesis approach wherein a mixed-integer nonlinear programming (MINLP) stagewise superstructure model is first solved, based off the model of Verheyen and Zhang (2006), to obtain the initial network across multiple periods. However, without taking into account the heat exchanger design details, such as velocities of streams, pressure drops, heat transfer coefficients, and number of shells, it is likely that the selected solution from the multi-period HEN model is sub-optimal, or even infeasible across certain periods of operation. Approaches to multi-period HEN synthesis have typically used the largest area across all periods as the optimal exchanger to represent the capital cost of the exchanger in the objective function. Heat exchanger networks (HENs) that are able to operate over all planned periods are termed multi-period HENs and have been the topic of significant research. In addition to the dynamic temperature and flowrate fluctuations that occur around a setpoint, many plants also operate with planned changes that may result from new product specifications, seasonal shifts in operating temperatures, batch operation, or with start-up and shutdown procedures. Heat exchangers are critical process units that are often required to operate over many operating conditions.