The supercritical carbon dioxide (sCO2) based Brayton cycle is a proposed alternative to replace conventional Rankine cycles in terms of high efficiency, compact turbomachinery and heat exchangers. In the sCO2 cycle, however, existing exchangers have been challenged by large portion transfer (approximately 60–70% total transfer) efficiency required. present study, two novel were utilizing triply periodic minimal surface (TPMS) structures. i.e. Gyroid structure Schwarz-D surface, enhance...

This paper proposes a novel concept of travelling-wave thermoacoustic electricity generator, which employs looped-tube engine to convert thermal energy into acoustic power, an ultra-compliant alternator within the loop extract and power stub matching technique match engine. In addition, carefully designed cold heat exchanger acts as phase shifting inertance improve performance. A simple model has been developed capture demonstrate physics this new concept, while whole system investigated in...

Air-cooled condensers are widely used for Organic Rankine Cycle (ORC) power plants where cooling water is unavailable or too costly, but they then vulnerable to changing ambient air temperatures especially in continental climates, the temperature difference between winter and summer can be over 40 °C. A conventional ORC system using a single component working fluid has designed according maximum thus operates far from optimal design conditions most of year, leading low annual average...

Organic Rankine cycle (ORC) system is considered as a promising technology for energy recovery from the waste heat rejected by internal combustion (IC) engines. However, such normally contained in both coolant and exhaust gases at quite different temperatures. A single ORC usually unable to efficiently recover of these sources. dual loop which essentially has two cascaded ORCs engine's separately been proposed address this challenge. In way, overall efficiency can be substantially improved....

Whether triply periodic minimal surface (TPMS) heat exchangers are applicable to cooling or cold storage systems as a cooler for supercritical carbon dioxide (SCO2) is undocumented. Here the conjugated transfer of SCO2 in TPMS Schoen-G exchanger and printed circuit (PCHE) was predicted based on three-dimensional steady turbulent Reynolds-averaged Navier-Stokes equations, energy equation shear stress transport model using computational fluid dynamics software ANSYS CFX when inlet temperature...

Biodiesel has the potential to mitigate fossil fuel-related carbon emission and energy insecurity challenges. There are limited studies examining impacts of biodiesel production scales on environmental impacts, while such information will be valuable for guiding practical system design. This work applied approach life cycle assessment evaluate from rapeseed oil which accounts 80% European biofuel market. It was shown that centralized large-scale localized small-scale schemes have annual...

Climate action is essential if global warming to be limited 1.5 °C and, and consequently, the transportation sector aims phase out fossil fuel vehicles, ensure that carbon net-zero can achieved by 2050. It expected batteries or hydrogen cells will most likely main driver of future zero-emission vehicles in order achieve target for transport. One key research challenges fully electric space heating/cooling cabin, which consumes a huge amount electricity through conventional methods. Moreover,...

The Kalina cycle is believed to be one of the most promising technologies for power generation from low temperature heat sources such as geothermal energy. So far, plants are designed with a working fluid mixture having fixed composition, and thus normally operate at condensing temperature. However, ambient (i.e., sink) varies over large range season changes year, particularly in continental climates. Recently, new concept, i.e., composition-adjustable cycle, was proposed develop that can...

The majority of the energy in fuel burned internal combustion engines is lost form waste heat. To address this issue, heat recovery technology has been proposed to increase overall efficiency engine. This paper investigates a driven cooling system based on supercritical CO2 (S-CO2) power cycle integrated with transcritical (T-CO2) refrigeration cycle, aiming provide an alternative absorption system. combined produce for food preservation refrigerated truck by In system, S-CO2 absorbs from...

Artificial neural network (ANN) has become an important method to model the nonlinear relationships between weather conditions, building characteristics and its heat demand. Due large amount of training data required for ANN training, reduction feature selection are simplify training. However, in demand prediction, many weather-related input variables contain duplicated features. This paper develops a sensitivity analysis approach analyse correlation detect that have high importance but The...

Anaerobic digestion (AD)-based biogas production mitigates the environmental footprint of organic wastes (e.g., food waste and sewage sludge) facilitates a circular economy. The work proposed an integrated system where thermal energy demand AD is supplied using air source heat pump (ASHP). compared to baseline system, by natural gas-based heating system. Several machine learning models are developed for predicting production, among which Gaussian Process Regression (GPR) showed superior...

Mechanical feed pumps in organic Rankine cycle (ORC) power plants can suffer from cavitation to lose their normal feeding performance or even damage. Cavitation models for fluids ORC systems are lacking presently. Hence, a new model with thermodynamic effect was proposed. Surface tension-controlled, inertia-controlled, intermediate and heat transfer-controlled regimes, two key elements: vapour bubble growth rate number density included the model. A known air non-condensable gas concentration...

To make carbon dioxide (CO2) heat exchangers in refrigeration systems more efficient and compact, passive methods for transfer enhancement produced by tubes various shapes were surveyed assessed. The classified into eight types proposed classification method based on their geometrical features. overall thermal-hydraulic performance of each type the individual elucidated using friction factor ratio, Nusselt number evaluation criteria (PEC) efficiency laminar turbulent flow regimes. A critical...

District heating uptake has grown with the increasing need for cleaner and more efficient energy supply. This resulted in a rising number of new developments signing up to district scheme, typically powered by Combined Heat Power (CHP) boilers or biomass supplemental electrical gas grid connections. These schemes have advanced rapidly recent years, much research focus targeting lower carbon technologies, improved load prediction peak demand management. We assess current status Heating...