Interplant heat exchanger network synthesis using nanofluids for interplant heat exchange

Abstract

Heat transfer between different processes or inter-plant heat integration can be seen as an efficient way to cost-efficiently improve the energy efficiency of a system of different processes. Nanofluids are a new type of heat transfer fluids, in which particles with size of 1-100 nm are suspended in a liquid. Nanosized particles can cause considerable enhancement in convective heat transfer performance of the base fluid, although at the same time they increase the viscosity of the fluid, thus enhancing the needed pumping power. In this work we study the effect of using nanofluids in streams transferring heat from different processes by optimizing the total annual cost of a heat exchanger network. These costs include the cost of hot and cold utilities, heat exchanger investment costs and pumping costs. A modified version of the well-known Synheat superstructure is used as the optimization model in comparing the different fluids (water and five nanofluids) in two examples. Some key parameters (electricity price and annuity factor) are varied in these two examples. The results show that nanofluids can in some cases save total annual costs and especially if electricity prices are low compared to other factors. This is true especially for M gO 1.0% which outperformed water and the other nanofluids in normal price conditions. But altogether it is evident that most, and in some cases all, of the benefits provided by nanofluids to improved heat transfer is canceled out by the increased pressure drops.

Incorporating Location Aspects in Process Integration Methodology

“…However, in order to keep the formulation linear, they made simplifying assumptions by using pre-calculated logarithmic mean temperature difference (LMTD) and pipe diameters. Laukkanen and Seppala [42] studied using nanofluids in inter-plant HEN synthesis. They developed a method to optimise the HEN, taking into account the trade-off between enhanced heat transfer and increased pumping power requirement due to the addition of nano-particles in the heat transfer fluid.…”

The design of the total site exchanger network with intermediate heat carriers: Theoretical insights and practical application

“…Inter-plant integration may be solved using such multiperiod optimisation minimising environmental impact [24]. Nano-fluids may also be used as intermediate for interplant integration, and it may be a cost-saving, in case of low electricity price [25]. Besides, interplant integration with non-isothermal utility loop may be represented with the use of transhipment type HEN model to avoid non-linear terms and simplify the model formulation [26].…”

Multiobjective Optimization of Interplant Heat Exchanger Networks Considering Utility Steam Supply and Various Locations of Interplant Steam Generation/Utilization

“…The concept of TSHI was first proposed by Dhole and Linnhoff, which consisted of multiple plants linked through a shared utility system, and the steam was utilized as an intermediate fluid. Laukkanen and Seppala used nanofluids as the intermediate fluid and studied the effect of nanofluids in enhancing the heat transfer performance. Considering the unique performance of the intermedium agent, the simultaneous utilization of multiple intermedium agents was explored in a recent interplant HEN design, and a cascade heat recovery was obtained .…”