• Energy Research

Research presented in this paper has received funding from: i) the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 680599, ii) Innovate UK (Project No. 61995-431253, iii) Engineering and Physical Sciences Research Council UK (EPSRC), Grant No. EP/P510294/1; iv) Research Councils UK (RCUK), Grant No. EP/K011820/1. The authors would like to acknowledge the financial support from these organisations as well as contributions from industry partners: Spirax Sarco Engineering PLC, Howden Compressors Ltd, Tata Steel, Artic Circle Ltd, Cooper Tires Ltd, Industrial Power Units Ltd. The authors also acknowledge contributions from Mr. Jonathan Harrison and Mr. Marek Lehocky of Gamma Technologies during the model development.

Highlights: • A solar-powered green hydrogen supply chain is designed for Kuwait in 2050. • Cost, carbon footprint, and safety are optimised for a hydrogen supply chain. • A hydrogen gas supply chain is generally more favourable than liquid. • Higher demand amplifies efficiency gains and operational savings. • Pipelines and salt caverns emerge as optimal transport and storage choices. Supplementary data are available online at: https://www.sciencedirect.com/science/article/pii/S0360319925014314?via%3Dihub#appsec1 . Located in the Arabian Gulf, Kuwait is a renewable-abundant country ideal for producing hydrogen via solar energy (green hydrogen). With a global transition away from fossil fuels underway due to their adverse environmental impacts, hydrogen is gaining significant traction as a promising clean energy alternative for the transport sector. Despite this, there are still various challenges associated with implementing a hydrogen supply chain, particularly with regard to the conflicting objectives of minimising cost, environmental impact and risk. This study determines the feasibility of implementing a green hydrogen supply chain in Kuwait based on a multi-objective design, to determine which combination of production (electrolysis type), storage method and transportation method is the most optimal for Kuwait. Three objective functions were considered in this study: the hydrogen supply chain cost, environmental impact, and safety/risk. A mathematical formulation based on mixed integer linear programming (MILP) was used, involving a multi-criteria approach where the three considered objectives must be optimised simultaneously, i.e., cost, global warming potential and safety/risk. The multi-objective optimisation approach via the weighted sum method was applied in this study and solved via GAMS. To account for the ranking of multi-objective criteria, a hybrid AHP-TOPSIS approach was used. Results showed that medium and high demand scenarios better reflect the comparative advantages of each considered method in terms of their multi-objective trade-offs. In particular, it was found that higher hydrogen demand amplifies the impact of higher efficiency and operational savings within several production, storage and transportation methods, and that despite higher initial capital investments, these costs are at some point offset by superior operational efficiency as hydrogen production volumes increase. Conversely, using highly efficient electrolysers or transportation methods at low demand was found to limit their performance. Ministry of Education, Science and Sports of the Republic of Lithuania and Research Council of Lithuania (LMTLT) under the Program ‘University Excellence Initiative’ Project ‘Development of the Bioeconomy Research Center of Excellence’ (BioTEC), agreement No S-A-UEI-23-14.

Abstract This paper provides a comprehensive description of the thermal conditions within a heat sink with rectangular fins under conditions of cooling by laminar forced convection. The analysis, in which increasing complexity is progressively introduced, uses both classical heat transfer theory and a computational approach to model the increase in air temperature through the channels formed by adjacent fins and the results agree well with published experimental data. The calculations show how key heat transfer parameters vary with axial distance, in particular the rapid changes in heat transfer coefficient and fin efficiency near the leading edges of the cooling fins. Despite these rapid changes and the somewhat ill-defined flow conditions which would exist in practice at the entry to the heat sink, the results clearly show that, compared with the most complex case of a full numerical simulation, accurate predictions of heat sink performance are attainable using analytical methods which incorporate average values of heat transfer coefficient and fin efficiency. The mathematical modelling and solution techniques for each method are described in detail.

Supplementary data are available online at https://www.sciencedirect.com/science/article/pii/S0360544222006326?via%3Dihub#appsec1 . In the current work, we demonstrate a simple, versatile, and scalable approach to synthesized silica encapsulated phase-change material (n-hexacosane) loaded between exfoliated-graphite nanosheets (ESPCM) by a chemical process (sol-gel and hydrothermal technique), exhibiting ultra-high thermal stability. The morphological, structural, and chemical properties of synthesized nanocomposite materials were investigated, and the results revealed that the PCM encapsulated within the silica shell was of diameters 120–220 nm and loaded in porous dendritic structures without any chemical reactions in phase change material. Further, the thermophysical properties such as latent heat, thermal conductivity, and stability of synthesized nanocomposites (ESPCM) were investigated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). During melting and solidification cycles, a solid-liquid phase transition of ESPCM nanocomposite was observed at 57.9 °C and 48.1 °C with a latent heat of 126.7 J/g and 117.6 J/g respectively. The ESPCM composites exhibited high thermal conductivity (15.74 W/m K) and ultra-high stability against thermal degradation after 300 thermal cycles. Subsequently, COMSOL simulations were carried out to investigate the thermal performance (heat flow with respect to time) of ESPCM, where, on increasing the EG concentration in the nanocomposite, an enhanced heat flow process was observed. CSIR - Council of Scientific & Industrial Research (09/1074(0004/2018 EMR-I); Heat Pipe and Thermal Management Research Group, Brunel University London, UK.

Abstract The ceramics industry is the second largest energy consuming sector in Europe. The main energy used in the ceramics industry is heat generated through burners using natural gas. The main area can be identified in three stages, the drying stage and the firing stage, and the cooling stage. The firing stage represents about 75% of the total energy cost. The roller hearth kiln technology is considered to be the most cost-effective solution for ceramic tile manufacturing. The kiln is separated into two sections, the firing stage and the cooling stage. The cooling stage generates large amounts of waste heat as the exhaust of the kiln is composed of a challenging flue gas for heat recovery. The recovery of this heat in an efficient way with no cross contamination has been achieved with a heat pipe heat exchanger (HPHE) system, which was designed, manufactured and installed on a roller hearth kiln and is presented in this paper. The heat pipe heat exchanger located next to the cooling section exhaust stack managed to recover up to 100 kW at steady state without cross contamination or excess fouling. The return on investment of the system has been evaluated at 16 months with a saving of £30,000 per year. This paper will present a deep row by row theoretical analysis of the heat pipe heat exchanger. The Computational Fluids Dynamics will also be presented to investigate the fluid dynamics within the evaporator and condenser section. Both investigations have then been validated by the experimental investigation carried out on a full-scale industrial system. The design approach used in this paper will highlight the benefits of this type of technology and provide a guideline for the design of novel heat pipe heat exchangers.

Abstract The introduction of low temperature renewable energy sources such as geothermal heat pumps into domestic central heating systems will demand that new technologies be developed to dissipate the required heat loads into homes. The main reason for this is the lower operating temperatures associated with these energy sources, which can be as low as 35 °C and rarely exceed 55 °C. Unless the appropriate heat exchanger is deployed, expensive and intrusive alternatives such as forced air convectors, under floor heating and home insulation retrofitting must be considered. This work details the development of a turn-key heat pipe based naturally aspirated convector for domestic central heating applications. The results show that the heat pipe convector design has a power density of nearly 3 times that of a popular off the shelf panel radiator as well as a finned-serpentine convector. Furthermore, the low water content associated with the heat pipes results in a unit with a much reduced thermal response time which could be advantageous in the context of building thermoregulation.

Heat pipe heat exchangers (HPHEs) are being more frequently used in energy intensive industries as a method of low-grade waste heat recovery. Prior to the installation of a HPHE, the effect of the heat exchanger within the system requires modelling to simulate the overall impact. From this, potential savings and emission reductions can be determined, and the utilisation of the waste heat can be optimised. One such simulation software is TRNSYS. Currently available heat exchanger simulation components in TRNSYS use averaged values such as a constant effectiveness, constant heat transfer coefficient or conductance for the inputs, which are fixed during the entire simulation. These predictions are useful in a steady-state controlled temperature environment such as a heat treatment facility, but not optimal for the majority of energy recovery applications which operate with fluctuating conditions. A transient TRNSYS HPHE component has been developed using the Effectiveness-Number of Transfer Units (ɛ-NTU) method and validated against experimental results. The model predicts outlet temperatures and energy recovery well within an accuracy of 15% and an average of 4.4% error when compared to existing experimental results, which is acceptable for engineering applications.