Energy Procedia最新文献

This work presents an approach to develop an innovative decarbonisation investment strategy framework for carbon intensive UK industries by using statistical analysis and optimisation modelling. The case study focuses on taking a representative sample of retail buildings and assesses the financial viability of installing low-carbon Combined Heat and Power units (CHPs) and Photovoltaic Solar Panels (PVs) across a portfolio of buildings. Simulation of each building are initially conducted, and the results generate a set of regression coefficients, via a multivariate adaptive regression splines (MARS), which are inputted into a Mixed Integer Linear Programming (MILP) problem. Solving the MILP yields the optimal decarbonisation investment strategy for the case study up to 2050, considering market trends such as electricity prices, gas prices and policy incentives. Results indicate the level of investment required per year, the operational and carbon savings associated, and a program for such investments. This method is reiterated for several scenarios where different parameters such as utility prices, capital costs and grid carbon factors are forecasted up to 2050 (following the Future Energy Scenarios from National Grid). This work shows how a clear mathematical framework can assist decision-makers in commercial organisations to reduce their carbon footprint cost-effectively and thus reach science-based targets.

Fly ash from a poultry litter gasification process and the potential of application of the fly ash as a fertiliser in line with the poultry litter protocol is investigated. The fines collected in the cyclone are mainly formed by ash which comprises between 70-83 wt.% of the fines on a dry basis, and to a lesser extent of carbon (elutriated char). The effect of the gasification operating conditions on the concentration of ash forming elements (inorganic compounds) in the fly ash, are discussed. In addition, the enrichment factor which defines the volatility, has been used and fly ash elements were categorised as Class I (non-volatile), Class II (semi-volatile with the possible occurrence of condensation) and Class III (highly volatile elements). Inorganic elements in fly ashes from poultry litter gasification experiments are categorised as Class I: Ca, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Class II: Cd, Cr, Mo and Class III: Pb and Se. It has been found that the fly ash from the poultry litter gasification exceeds the upper acceptable limit set by Poultry Litter Protocol to be used as a fertiliser in agriculture systems.

The paper focuses on understanding the performance of a vaned diffuser in a supercritical CO₂ compressor using real gas assumptions. The rapidly changing properties of CO₂ in the non-ideal thermodynamic region can have a significant impact on the performance of the diffuser. To account for this, the relationship between the flow properties (i.e. fundamental derivative) and the local geometry (i.e. cross-sectional area of the nozzle) has been discussed theoretically. To examine it analytically, the study has considered the influence of real gas properties on the performance of a vaned diffuser using computational fluid dynamics (CFD) modelling. The selected compressor stage geometry is similar to the compressor impeller tested in the Sandia sCO₂ compression loop facility. The effect of changes in the number of blades and the corresponding changes in the cross throat area on the flow properties such as density and speed of sound were investigated and discussed. The results illustrate that a diffuser with a higher number of blades (smaller throat area) compared to a diffuser with a wider throat area has a higher probability of creating flow instability in the passage stage.

The experimental work evaluated the thermal performance of a new panel design to encapsulate Phase Change Material (PCM) and compare this with an existing panel commercially available and incorporated within a PCM-Air heat exchanger system. The analysis was focused on the melting and solidifying time of the PCM within each panel design. It also focused on the thermal load of the ‘Latent Thermal Energy Storage’ (LTES) of a thermal battery module, each battery module consisting of multiple panels stacked together with an air gap between each panel. The existing battery modules consisted of 9 panels while the new module has 7 panels, with all panel filled with an industry recognised PCM. The new design battery module is now able to hold 17.5 kg more PCM than the existing one, resulting in 30% more material than the existing module. The air temperature used for melting and solidifying was 30°C and 15°C respectively, with a constant airflow of 75 l/s. Tests were carried out first with one battery module and then with an additional battery module in series and compared with a three-layer-calorimeter test (3LC). The results of the new design battery indicated an increase in time to melt and solidify the PCM due to the additional material within each battery module.

A pilot scale investigation of co-pyrolysis of biological dairy sludge and spruce wood chips and pyrolysis of spruce wood chips solely was carried out. Pyrolysis was tested as a waste treatment method aiming to reduce the volume of dairy sludge while producing a pyrolysis gas suitable for an internal combustion engine. Pyrolysis tests were carried out in a continuously fed, pilot scale rotating retort type of facility in the temperature range between 700 and 770 °C. Feedstock feeding rates were between 40.9 – 68.6 kg_d.a.f. h^-1. Tar yields and composition was measured by means of the solid phase adsorption method in order to assess gas quality with regard to the specified tar limits given for downstream applications. The yields of total gas chromatography detectable tar produced from the dairy sludge and spruce wood chips blend was in the range between 7.25 - 10.98 g_{total tar} Nm^-3 _{dry raw gas}, while spruce wood chips solely produced yields between 11.18 - 13.31 g_{total tar} Nm^-3 _{dry raw gas}. Composition wise, the main difference was a number of nitrogen-containing tar compounds reflecting the high nitrogen content in dairy sludge feedstock with 2-butenenitrile, pyridine and 1H-pyrrole being the most abundant nitrogen-containing tar compounds. Raw pyrolysis gas from the two feedstocks tested did not meet the requirements regarding tar limits given in the manufacturer’s specification for their internal combustion engine. The raw pyrolysis gas contained excessive amounts of 3 and 4+ aromatic ring tars. Therefore tar removal is required prior to combustion in the engine. The proposed tar removal strategy includes a thermal tar reformer using air as a reforming agent followed by adsorption using wood chips, or in-process generated bio-char, or torrefied biomass as a viable adsorbent.

Addressing GHG emissions from industry is vital to achieving decarbonisation targets. However, finding alternatives to many industrial energy requirements remains a challenge. Many processes in the food sector require heat at relatively low temperatures (i.e. 80°C to 200°C). High temperature heat pumps under development present a heat source that is efficient (especially if coupled with waste heat sources) and low carbon (especially if powered by decarbonised electricity). This study analysed their potential in the UK Dairy sub-sector and extrapolates this to the wider Food and Drink sector. There is potential to save approximately 164 kt-CO₂/yr in the modelled processes. Applied to similar processes across the Food and Drink sector, there is scope to save 2.6 Mt-CO₂/yr with projected 2030 grid electricity emissions factors. High temperature heat pumps have the potential to save energy and reduce GHG emissions. These GHG savings will increase further as the electrical grid continues to be decarbonised. While fuel cost savings are possible, these depend upon the processes and become more significant with projected fuel prices.

A series of experiments were performed on industrial baking ovens across five confectionery manufacturing sites around the world. The impact of different operating parameters such as air and fuel flowrates, oven temperature, exhaust flowrates and ambient temperature etc., on the product quality and overall oven performance were investigated. The energy flows through the baking oven were modelled using experimentally determined inputs to estimate the reduction in heat losses. A step change in operational efficiency was achieved through the study delivering 8.5% improvement in the oven performance. On average, 92 tonnes/annum of CO2 were saved from each oven. An additional 7% efficiency improvement was observed by integrating the baking oven with a heat recovery technology saving circa £16k in fuel cost annually from a single oven. The observations and learnings from the work are not limited to baking ovens only, but can also be applied to other food manufacturing processes such as frying, broiling, roasting or grilling.

The human relationship with food is an under-acknowledged contributor towards climate change and environmental degradation. However, citizens’ choices and actions regarding food consumption and production in urban settings are shaped by the economic, cultural and infrastructure systems in which they live. The purpose of this paper is to examine, from the perspective of prosumers, the socio-technical factors that affect urban food production and associated energy, water and waste services. A residential development on the urban fringe of Australia’s subtropical Gold Coast was used as a case study. A mixed methods approach was utilised to gather quantitative and qualitative data through estate maps, development planning documents, visual observations, interviews and surveys. Data was analysed around the themes of food production, consumption and development infrastructure (physical and social). The estate’s food production demonstrated high biodiversity and highlighted three common challenges: biological, knowledge and water/climate. Food consumption incorporated self-consumption, sharing/trading and a range of other typical and atypical sources found in cities. An integrated approach to land-use, energy, water and waste was instrumental in enabling food production, highlighting issues that affect the ability of urban prosumers to incorporate sustainability into their food practices. The paper raises the possibility of a ‘sharing-economy’ food production typology for urban areas and proposes an initial performance indicator framework (people, planet, prosperity, governance and propagation) to understand, develop and manage urban prosumers in the context of integrated energy, water, waste and food services.

Instant coffee manufacture involves the aqueous extraction of soluble coffee components followed by drying to form a soluble powder. A challenge that arises from the process is the loss of volatile aroma compounds during evaporative drying. One method of retaining aroma is to first steam strip the volatiles from the coffee and add them back to a concentrated coffee solution just before the final drying stage. Understanding the impact of process conditions on the aroma content of the stripped solution offers engineers the ability to target desirable compounds and maximise their yield. This paper presents a multiscale model for aroma extraction that describes: (i) release from the matrix, (ii) diffusion through the coffee grain, (iii) transfer into water and steam, and (iv) advection through the stripping column. Results reveal how aroma physiochemistry determines the limiting kinetics at industrial extraction conditions. The interaction with the soluble matrix can also inhibit extraction, but this effect varies for the different aromas studied.

Thermal energy storage (TES) using phase change materials (PCMs) is a dynamically growing research area. The interest in this research field can be illustrated by the increasing number of research papers published in the last few years. In this comprehensive paper the latest reports in the field of phase change materials studies and their application in thermal energy storage are discussed. Main review articles on PCMs properties and applications are provided. Special attention is given to very recent publications providing information on PCMs nano, micro and macro encapsulation as well as on materials aspects critical for PCMs application in TES. This paper may be a useful guide for the researchers towards a short overview of current status of PCM science and technology.