Optimum heat exchanger area estimation using coefficients of structural bonds: Application to an absorption chiller

The optimum allocation of the heat exchange area considers both running and investment cost. The structural method of thermoeconomic optimization is used to derive a simple equation for the estimation of the economic optimum of the area of a heat exchanger integrated in a more complex system. The obtained equation is generally valid for thermal systems. The optimum heat exchange area can be estimated in a straightforward calculation once operation and cost parameters, the overall heat transfer coefficient and the Coefficient of Structural Bonds (CSB) are known. The CSB quantifies the interactions between the units of the thermal system and is obtained from an exergy analysis. Therefore, compared to former work, the proposed equation has the advantage of considering interactions between the units of the system. A case study is presented for an ammonia-water absorption chiller. The optimum area from the proposed formulation is compared with the results obtained from the integrated optimization algorithm of EES (from F-Chart) and the base cases for different annual operation time.