Browsing by Author "Cleland DJ"

Now showing 1 - 5 of 5
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    Advancing Industrial Process Electrification and Heat Pump Integration with New Exergy Pinch Analysis Targeting Techniques
    (MDPI (Basel, Switzerland), 2024-06-08) Walmsley TG; Lincoln BJ; Padullés R; Cleland DJ; Rosato A
    The process integration and electrification concept has significant potential to support the industrial transition to low- and net-zero-carbon process heating. This increasingly essential concept requires an expanded set of process analysis tools to fully comprehend the interplay of heat recovery and process electrification (e.g., heat pumping). In this paper, new Exergy Pinch Analysis tools and methods are proposed that can set lower bound work targets by acutely balancing process heat recovery and heat pumping. As part of the analysis, net energy and exergy load curves enable visualization of energy and exergy surpluses and deficits. As extensions to the grand composite curve in conventional Pinch Analysis, these curves enable examination of different pocket-cutting strategies, revealing their distinct impacts on heat, exergy, and work targets. Demonstrated via case studies on a spray dryer and an evaporator, the exergy analysis targets net shaft-work correctly. In the evaporator case study, the analysis points to the heat recovery pockets playing an essential role in reducing the work target by 25.7%. The findings offer substantial potential for improved industrial energy management, providing a robust framework for engineers to enhance industrial process and energy sustainability.
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    Heater choice, dampness and mould growth in 26 New Zealand homes: A study of propensity for mould growth using encapsulated fungal spores
    (MDPI AG, 2015) Boulic M; Phipps RA; Cunningham MJ; Cleland DJ; Fjallstrom P; Keiko P; Howden-Champan P
    The relationship between the use of unflued gas heaters (UGH, N = 14) and heat pump heaters (HP, N = 12) located in the living rooms, and mould growth on the living room and bedroom walls, of 26 New Zealand (NZ) occupied homes was investigated during winter. Two methods were employed to evaluate the potential of mould growth on walls: (i) measurement of daily hyphal growth rate using a fungal detector (encapsulated fungal spores); and (ii) estimation of fungal contamination based on a four level scale visual inspection. The average wall psychrometric conditions were significantly different between the two heater type groups, in both the living rooms and the bedrooms with the UGH user homes being colder and damper than HP user homes. The UGHs were found to be a significant additional source of moisture in the living rooms which dramatically increased the capacity for fungi to grow on wall surfaces. The average daily hyphal growth rates were 4 and 16 times higher in the living rooms and in the bedrooms of the UGH user homes, respectively. Results from both mould detection methods gave good agreement, showing that the use of a fungal detector was an efficient method to predict the potential of mould growth on the inside of the external walls in NZ homes.
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    High-temperature and transcritical heat pump cycles and advancements: A review
    (Elsevier Ltd, 2022-10) Adamson K-M; Walmsley TG; Carson JK; Chen Q; Schlosser F; Kong L; Cleland DJ
    Industrial and large-scale heat pumps are a well-established, clean and low-emission technology for processing temperatures below 100 °C, especially when powered by renewable energy. The next frontier in heat pumping is to extend the economic operating envelope to supply the 100–200 °C range, where an estimated 27% of industrial process heat demand is required. Most high-temperature heat pump cycles operate at pressures below the refrigerant's critical point. However, high-temperature transcritical heat pump (HTTHP) technology has - due to the temperature glide – a significant efficiency potential, especially for processes with large temperature changes on the sink side. This review examines how further developments in HTTHP technology can leverage innovations from high-temperature heat pump research to respond to key technical challenges. To this end, a comprehensive list of 49 different high temperature or transcritical heat pump cycle structures was compiled, which lead to classification of 10 performance-enhancing cycle components. Focusing specifically on high-temperature transcritical heat pump cycles, this review establishes six technical challenges facing their development and proposes solutions for each challenge, including a new transcritical-transcritical cascade cycle innovation. A key outcome of the review is the proposal of a new cycle that requires detailed investigation as a candidate for a high-temperature transcritical heat pump cycle.
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    Multi-Level Process Integration of Heat Pumps in Meat Processing
    (MDPI (Basel, Switzerland), 2023-04-13) Klinac E; Carson JK; Hoang D; Chen Q; Cleland DJ; Walmsley TG; Zuorro A; Papadopoulos AI; Seferlis P
    Many countries across the globe are facing the challenge of replacing coal and natural gas-derived process heat with low-emission alternatives. In countries such as New Zealand, which have access to renewably generated electricity, industrial heat pumps offer great potential to reduce sitewide industrial carbon emissions. In this paper, a new Pinch-based Total Site Heat Integration (TSHI) method is proposed and used to explore and identify multi-level heat pump integration options at a meat processing site in New Zealand. This novel method improves upon standard methods that are currently used in industry and successfully identifies heat pump opportunities that might otherwise be missed by said standard methods. The results of the novel method application suggest that a Mechanical Vapour Recompression (MVR) system in the Rendering plant and a centralized air-source heat pump around the hot water ring main could reduce site emissions by over 50%. Future research will develop these preliminary results into a dynamic emissions reduction plan for the site, the novel methods for which will be transferrable to similar industrial sites.
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    Thermo-economic investigation and multi objective optimization of cascade high temperature heat pump using low global warming refrigerants
    (Elsevier B.V., 2025-11-15) Hoang DK; Walmsley TG; Cleland DJ; Chen Q; Carson JK
    High temperature heat pumping (HTHP) is a key technology for decarbonizing industrial process heat. This paper describes an investigation into the thermodynamic and economic performance of a cascade HTHP configured with internal heat exchangers (IHXs), using low global warming potential (GWP) refrigerants in both the top cycle and the bottom cycle. The proposed system was applied to a spray dryer case study with supply air temperature over 200 °C. A differential evolution (DE) method was used to optimize operating parameters to obtain the maximum COP. The simulation results indicated that of the cycles and refrigerants considered, the maximum COP can be obtained when using acetone or ethanol in the top cycle (TC) and butane or neopentane in the bottom cycle (BC). The use of acetone/neopentane and ethanol/neopentane achieved a highest COP of 2.42; however, better economic performance was achieved when using butane as the BC refrigerant rather than neopentane, while the economic and thermodynamic performance of the heat pumps were similar when acetone and ethanol were used as TC refrigerants. The performance of the most promising refrigerants was analyzed under off-design conditions, with minimum and maximum COP being 2.19 and 2.82, respectively obtained with the sink inlet/outlet temperature of 50 °C/230 °C and 15 °C/200 °C.