John M. Allport

Hydropower in the United Kingdom (UK) remains underexplored due to its dependence on site‐specific geographical and hydrological conditions. This study aims to assess the technical and economic feasibility of installing a small‐scale hydropower system at an existing weir on the River Colne. Hydrological assessment was conducted using a 95% dependable flow duration curve (FDC) to estimate available flow and power output, while system performance and economic viability were evaluated using RETScreen modelling and sensitivity analysis. Results indicate a maximum capacity of 76.5 kW and annual generation of 284,384 kWh, offsetting approximately 3235 tonnes of CO ₂ . Economic analysis yields a net present value (NPV) of £322,769, a benefit‐cost ratio of 4.5, an internal rate of return of 9.4% and a levelised cost of electricity (LCOE) of £0.132/kWh, with simple and equity payback periods of 15.3 and 17.2 years, respectively. The findings confirm technical and economic viability and provide a replicable framework for site‐specific hydropower assessment in the UK.

England holds significant potential for hydropower development, yet various challenges including environmental concerns continue to limit extensive deployment. This study offers an interdisciplinary analysis of the key barriers hindering hydropower expansion in England, focusing on institutional, policy, financial, and environmental factors. Findings reveal that fragmented regulations, unstable policy frameworks, and insufficient financial incentives collectively constrain the sector's progress. To overcome these obstacles, the study recommends enhanced coordination among relevant stakeholders, the establishment of more consistent policy environments, improved financial support mechanisms, and a review of environmental regulations to better balance development and conservation goals. These insights aim to inform policymakers and guide strategic planning for small‐scale hydropower in England. As the whole UK strives to diversify its renewable energy mix and achieve net zero emissions, addressing these barriers is critical for unlocking hydropower's contribution to a sustainable energy future.

As climate changes become more severe and the transition towards sustainability goals more important than ever, the need to modify our vehicles and their thermal management systems takes priority. The vast majority of Original Engine Manufacturers might be looking at the electrification of most vehicles, but it is equally important to make sure that our Internal Combustion Engine powered vehicles become more sustainable since most of our heavy transport is powered by ICEs. The biggest disadvantage of an ICE-powered vehicle is its emissions output. The engine emissions regulations have become stringent over the past few years leading to an increased emphasis on NOx reduction techniques. Air Cycle Technology (ACT) has created a novel form of turboexpander which has previously been tested by ACT in race car engines to reduce pre-ignition. This current work being reported has been carried out to prove the useability of the ACT turboexpander in diesel engines to reduce NOx formation by cooling the intake air. The engine used for this study is a 4.4-liter JCB-TCA 74 turbocharged diesel engine. The ACT turboexpander was retrofitted to the JCB engine. During the study performed on the JCB engine, second-stage cooling provided by the turboexpander showed a reduction of approximately 30° C in intake air temperatures. This data was also supported by hand calculations performed using empirical formulas.

The aim of this work is to design a piezoelectric power generation system that extracts power from the vibration of a cantilever beam. A semi-cylinder placed in a water stream and attached to the beam is excited into vortex-induced vibrations (VIV), which triggers the piezoelectric deformation. The mechanical system is modelled using parametric equations based on Hamilton’s extended principle for the cantilever beam and the modified Van der Pol model for the bluff body (the semi-cylinder). These equations are simulated using the MATLAB software. The dimensions of the model, the flow velocity and the resistance are treated as design parameters and an optimization study is conducted using MATLAB to determine the combination of optimal values at which maximum power is extracted. The key findings of this research lie in the identification of the effect of changing the design parameters on output power. In addition to the numerical simulation, a finite element analysis is carried out on the bluff body and the hydrodynamic forces and velocity profiles are observed. It is determined that the vibration amplitudes increase with increasing diameter of the bluff body, length of the bluff body and water velocity.

Centrifugal turbomachines of smaller sizes operating at higher speeds have become pervasive due to the increased specific power and reliability achieved by improvements in manufacturing, materials and computational methods. The presence of these small turbomachines, specifically compressors, in helicopters, unmanned aerial vehicles, auxiliary power units, turbochargers and micro gas turbines necessitates superior aerodynamic performance over a broad operational range, which is widely achieved by ported shroud casing designs. In addition to aerodynamic performance, acoustic emissions have become a critical aspect of design for these small centrifugal compressors due to high operational speeds. Furthermore, the literature on the acoustic effects of the casing treatment is rather limited. Therefore, the impact of ported shroud casing treatment on the acoustic and flow features of the compressor operating at the design and near-surge conditions have been quantified by numerically modelling the open and blocked configuration of the compressors. Upon comparing with experimental results, the numerical spectra are shown to capture the differences between the two configurations at the investigated operating points with reasonable accuracy. Although the casing treatment is generally seen to decrease the overall acoustic emission of the compressor at both operating conditions, increased propagation of tonal content in the direction upstream to the impeller is observed, particularly for design operation. Broadband characteristics in the lower and medium frequency regions usually associated with near-surge operation including ‘whoosh’ noise are observed to be alleviated by the ported shroud casing treatment.

In this article, the acoustic characterisation of a turbocharger compressor with ported shroud design is carried out through the numerical simulation of the system operating under design conditions of maximum isentropic efficiency. While ported shroud compressors have been proposed as a way to control the flow near unstable conditions in order to obtain a more stable operation and enhance deep surge margin, it is often assumed that the behaviour under stable design conditions is characterised by a smooth, non-detached flow that matches an equivalent standard compressor. Furthermore, research is scarce regarding the acoustic effects of the ported shroud addition, especially under the design conditions. To analyse the flow field evolution and its relation with the noise generation, spectral signatures using statistical and scale-resolving turbulence modelling methods are obtained after successfully validating the performance and acoustic predictions of the numerical model with experimental measurements. Propagation of the frequency content through the ducts has been estimated with the aid of pressure decomposition methods to enhance the content coming from the compressor. Expected acoustic phenomena such as ‘buzz-saw’ tones, blade passing peaks and broadband noise are correctly identified in the modelled spectrum. Analysis of the flow behaviour in the ported shroud shows rotating structures through the slot that may impact the acoustic and vibration response. Further inspection of the pressure field through modal decomposition confirms the influence of the ported shroud cavity in noise generation and propagation, especially at lower frequencies, suggesting that further research should be carried out on the impact these flow enhancement solutions have on the noise emission of the turbocharger.