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.

The global production of poultry is predicted to grow considerably in the future. Intensive poultry farming poses significant challenges to traditional waste disposal methods (i.e. direct land application) leading to environmental impacts. This paper discusses the result of low temperature (350-450 °C) pyrolysis of representative chicken litter as the feedstock. Four different feedstocks comprised of 50% organic chicken manure and 50% bedding materials (i.e. hay, straw, rice husk and wood shavings) have been experimentally investigated. The products of the pyrolysis process consist of char, gas and liquid (bio-oil). Maximum char production from the rice husk mix is over 67 wt.%, while the wood shavings mix feedstock resulted in the highest liquid yield of 44.4 wt.% at a temperature of 400 °C. Chicken litter and its char product are analysed by elemental analyser and bomb calorimetry. The composition of the evolved gases and bio-oil are analysed by micro gas chromatography (µ-GC) and gas chromatography-mass spectrometry (GC-MS), respectively. In addition, the mass and energy balance of the pyrolysis process are presented.

Most food products are currently processed in large, centralised factories with delocalised retail systems, which allows food processors benefit from economies of scale. This is efficient in terms of production, but can involve lengthy and rigid supply chains, with higher transport costs and environmental impacts. Decentralised manufacturing, based on local production at small scale, has risen recently as an alternative that could provide flexibility to the food supply chain. In this work we present a modelling tool for the design, evaluation and comparison of food manufacturing processes that considers economic, environmental and social factors. The proposed method can be applied to a wide range of food products and is illustrated here using cereal porridge and sandwich bread production. We have assessed and compared three decentralised scenarios: “Home Manufacturing” (HM), “Food Incubator” (FI) and “Distributed Manufacturing” (DM) to centralised production –i.e. Single Plant (SP) and Multi Plant (MP) scenarios. Based on UK demand, SP is the most energy efficient and cheapest scenario in both cases, closely followed by HM and FI in cereal porridge production. DM could compete with SP assuming low management costs and savings on transportation/storage along the supply chain. For the case study on bread, the shorter margin of profit per unit makes decentralised scenarios less advantageous.

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.

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.

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.