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The aim of this paper is to use Monte Carlo Simulation (MCS) to conduct an analysis of the flexibility and controllability of retrofitted Heat Exchanger Network (HEN) designs. Historical plant data is often uncertain and variable but is an important tool for understanding the real-time operation of a HEN. MCS uses these uncertainties to give an analysis of the retrofitted HENs, and it can be used in a more detailed analysis of the controllability and flexibility. Using Monte Carlo Simulation, inflexibility has been defined as the probability of a HEN to fail to meet temperature targets within defined tolerances. Inflexibility can be used as a tool to guide the retrofit analysis of a HEN. A retrofit HEN design should improve the flexibility of the network without compromising on the expected energy savings. The proposed method is demonstrated using a four-stream HEN problem. The inflexibility of the network was shown to be improved with bypass control and optimal allocation of retrofit area and the proposed method succeeds in augmenting the retrofit design method so that costeffective, flexible retrofit HENs can be identified. [ABSTRACT FROM AUTHOR]

The dairy processing industry is considered as energy-intensive processes between New Zealand industries that use fossil fuels as a primary energy source which results in greenhouse gas emissions as well as raising other environmental impacts. To mitigate the environmental impacts of fossil fuels that are used in dairy processing plants, it is essential to design a pathway moving from fossil-based energies towards renewable energy sources in a transition period. To do so, Life Cycle Assessment (LCA), as a standardised approach, has been implemented to quantify the environmental profile of different products by evaluating the environmental impacts of product systems. In this paper, three impact categories are considered adopting accessible inventory databases that match the regional and local data along with ReCiPe as the life cycle impact assessment method. These impact categories are 1) human health; 2) ecosystem; and 3) resources. Each category contains subcategories; seven different-statistically discernible energy mix scenarios (moving from coal through natural gas towards biomass) assisted by Monte Carlo simulation are defined to assess environmental impacts. Furthermore, Cumulative Exergy Demand (CExD) as an aggregated criterion has been exploited to indicate the sustainability of the whole system. Results show that for a cheese production process a biomass based scenario has the lowest environmental burden impact in 13 impact categories out of 14 studied impacts. Indeed, it has the lowest CExD with 1.05x10-5 MJ-Eq while surprisingly natural gas based scenario has the highest environmental burden with CExD of 3.85x10-1 MJ-Eq followed by coal with 4.73x10-4 MJ-Eq. [ABSTRACT FROM AUTHOR]

Heat pumps are the key technology to decarbonise thermal processes by upgrading industrial surplus heat using renewable electricity. Existing insight-based integration methods refer to the idealised Grand Composite Curve requiring the full exploitation of heat recovery potential but leave the question of how to deal with technical or economic limitations unanswered. In this work, a novel Heat Pump Bridge Analysis (HPBA) is introduced for practically targeting technical and economic heat pump potential by applying Coefficient of Performance curves into the Modified Energy Transfer Diagram (METD). Removing cross-Pinch violations and operating heat exchangers at minimum approach temperatures by combined application of Bridge Analysis increases the heat recovery rate and reduce the temperature lift to be pumped at the same time. The insight-based METD allows the individual matching of heat surpluses and deficits of individual streams with the capabilities and performance of different market-available heat pump concepts. For an illustrative example, the presented modifications based on HPBA increase the economically viable share of the technical heat pump potential from 61% to 79%. [ABSTRACT FROM AUTHOR]