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Heat Transfer & Design

The first objective of this research theme is to deliver the fundamental understanding of heat transfer mechanisms in the AGGAT environment which when applied, will lead to optimized heat transfer, scale and corrosion-resistant heat exchangers used for transferring heat between sources & operating cycle fluid. This will be achieved by studying scale attachment mechanisms and their influence on heat transfer, targeting a wide range of materials with surface treatment variations from plain surfaces to welded joints. This research will also impact allied industries that can benefit from using durable surfaces in their heat transfer processes.

Investigation is focused on a selected range of primary fluids and operation conditions, fouling, corrosion and its influence on heat transfer behaviour on base materials and selected surface modifications based on results from binary fluids and materials research (see Binary Fluids). A new multi sample test rig is being designed and commissioned to allow testing of a very-large number of samples on a comparative basis under identical conditions. This testing facility will also allow simulation of scale reducing measures such as acid dosing or maintenance processes such as Cleaning in Place (CIP). These will allow the growth of a comprehensive fouling testing capability which will serve the program partners. The outcomes from this objective will establish a performance ranking of the different materials and their surface modification and the results will be implemented into the EDT (see Technology Concepts).

The second objective is to implement the results of applied techniques on heat transfer efficiency of different designs of heat exchangers under a selection of primary fluids with differing operating conditions. Numerical modelling and testing with the developed test rig will verify model and design approach taken. Research of scale up issues especially around fluid flow and heat transfers will be the key for successful modularisation of the components. Novel heat exchanger design concepts likely to include foamed metals and ceramic surfaces will be trialled meeting the specific improvement requests identified during the research roadmap process.

Materials knowledge base

A significant factor influencing thermodynamic performance and plant reliability is the material of construction and its treatment. Cost-effective materials that can enhance plant performance and reduce maintenance requirements are a major focus of investigation in the AGGAT programme. The objective of this project is to devise material research algorithms for systematic investigation of their properties under modified environments and to compile this information for convenient access to support design decisions. The research plan spans the categories of material types, material surface treatments, fluid properties, environmental conditions as well as materials processing such as welding. This investigation is being led by Dr. Michail Karpenko with investigation including laboratory and field-based testing.

Modelling of Scaling Mechanism

Scaling is a common phenomenon in geothermal environments and a problem for plant performance especially in the context of heat transfer and plant maintenance requirements. Due to its severe impact on heat transfer and processing, understanding of the scaling mechanism is of significant value and this is being investigated by Dr. Mathieu Sellier who is leading this work stream using numerical techniques for modelling and simulation of silica scaling. Investigations include analysis of modelled expectations and their correlations with actual results as input to heat exchanger design for optimum heat transfer, corrosion-resistance and scaling across a variety of fluids and operating parameters. A wide range of materials with surface treatment variations from plain surfaces to welded joints is targeted for investigation. This research will also impact allied industries that can benefit from using durable surfaces in their heat transfer processes.

Heat Transfer Performance Data

A major indicator of plant performance is its heat transfer effectiveness which is governed by the properties of primary/binary fluids and materials as well as operating conditions. The need for physical assessment of these variables under controlled conditions exists in order to develop reliable predictive relationships between parameters and their effect on heat transfer results. This investigation is being carried out in this project under the leadership of Dr. Mark Jermy and investigates the potential for fouling, scaling and corrosion in a series of heat transfer conditions. Maintenance methods such as clean in place and chemical/mechanical surface treatments will be investigated for their effect on heat transfer performance under controlled thermodynamic and fouling conditions. The results from this work will be integrated with materials studies to compile an intelligent list of materials, conditions and performances to inform design decisions.

Heat Exchanger Technology

The technologies trialled under controlled physical (hydrodynamic and thermodynamic) conditions for heat transfer performance require assessment in processing environments using fully developed heat exchanger flow profiles. The objective of this project is to assess the success of heat transfer technologies developed under controlled hydrodynamic and thermodynamic conditions and to validate their validity under real scenarios. This project is progressing under the supervision of Dr. Sid Becker in collaboration with research work being undertaken in projects for materials and heat transfer performance.