Energy Conversion Units Research Articles

A carbon integrated energy pricing strategy based on non-cooperative game for energy hub in seaport energy system

Seaports are significant energy consumers and sources of carbon emissions within the maritime industry. To address this problem, an energy hub (EH) can be established as an intensive energy interconnection center. This paper proposes a carbon emission flow (CEF) model based on the energy hub in seaport, which monitors the carbon emissions generated by the internal energy conversion unit operating within the hub. Additionally, a carbon integrated energy pricing strategy based on non-cooperative game theory is proposed. Based on duality theory and gradient descent method, an iterative algorithm is designed to seek the global optimal solution satisfying the Nash equilibrium point. The aim of the strategy is to encourage seaport energy consumers to adjust their energy consumption strategy according to the optimal benefits and reduce carbon emissions. A comparative study of three different strategy cases are conducted to evaluate the effectiveness of the proposed strategy. Numerical simulation results show the reduction of the total energy consumption and carbon emissions of the system, which is conducive to realizing the low-carbon operation of the seaport energy system.

An LCC-CS bilateral matching network for high efficiency energy conversion in high-frequency piezoelectric rotary ultrasonic machining system

The processing efficiency and machining quality of piezoelectric rotary ultrasonic machining (PRUM) system are closely related to its electromagnetic energy conversion units and electroacoustic energy conversion units. Generally, the high efficiency and high-power capacity of PRUM systems are limited by several energy conversion devices including the capacitive piezoelectric transducer (PT) load, loosely coupled rotating transformer (RT), and non-soft switching inverter. This article improves the overall performance of high-frequency PRUM system by bilateral matching network. On the rotating side, the compared results of five different static matching schemes show that the CS matching scheme ensures stable and efficient vibration of capacitive PTs even under incomplete matching. On the stationary side, a dynamic LCC matching scheme is adopted to keep the output impedance angle of H-bridge inverter in the weak inductive state. Finally, the proposed high-order matching network in this article makes the efficiency of high-frequency PRUM system over 90 % steadily.

From exergoeconomics to Thermo-X Optimization in the transition to sustainable energy systems

Exergoeconomics has played an important role in the study of new energy systems in the last decades. The use of exergy as a “carrier of value” has made it possible to define an unambiguous criterion for allocating costs among energy systems products. The paper shows how exergoecomic procedures of analytical optimization and design improvement on heuristic basis have been progressively replaced by more efficient procedures aimed at minimizing an objective cost function, leaving exergoecomic cost evaluation as the final step. It also highlights how growing concerns about climate change and the continued growth of inequalities in energy availability have broadened the set of objectives in the search for the optimal integration of the design and operation of energy conversion units and network with intelligent methodologies to reduce energy demands. The objective of the article is twofold: i) present the evolution of the main Exergoeconomic methods and show how they have paved the way for Thermo-X Optimization methods; and ii) outline the path for developing a general model of society's entire energy system that includes a broader set of objectives and constraints in addition to economic ones to help build the energy system of the future with a more sustainable perspective.

Low-Carbon Optimal Configuration of Integrated Electricity and Natural Gas Energy System with Life-Cycle Carbon Emission

In response to the challenges of global warming and the development of A low-carbon economy, the integrated electricity and natural gas energy system (IEGES) is known as an important structure for future energy supply; thus, its planning and design must take low-carbon and environmental protection factors into account. Regarding carbon emissions as an optimization criterion, this paper built life-cycle carbon emission models of IEGES components. Then, taking the capacities of the energy resources, storage and conversion units of IEGES as the optimization variables, a multi-objective optimization configuration model was established considering the annual investment operation cost and the life-cycle carbon emissions. The multi-objective model was transformed into a single-objective one by an ε-constraint approach and the polynomial fitting method was employed to obtain the value of ε for obtaining uniformly distributed Pareto sets. Based on the fuzzy entropy weight method and the fuzzy affiliation degree approach, the obtained Pareto sets were ranked and the solution with the highest ranking value was selected as the optimal solution for the original problem. Finally, the configuration schemes were analyzed from the perspectives of economy, carbon emission and renewable energy utilization, and the effectiveness and rationality of the proposed optimization method were verified through MATLAB simulation.

Nonlinear Optimal Control for a PMLSG-VSC Wave Energy Conversion Unit

This article aims to treat the nonlinear control problem for the complex dynamics of a wave energy unit (WEC) that consists of a Permanent Magnet Linear Synchronous Generator (PMLSG) and a Voltage Source Converter (VSC). The article has developed a globally stable nonlinear optimal control method for this wave power generation unit. The new method avoids complicated state-space model transformations and minimizes the energy dispersion by the control loop. A novel nonlinear optimal control method is proposed for the dynamic model of a wave energy conversion system, which includes a Permanent Magnet Linear Synchronous Generator (PMLSG) serially connected with an AC/DC three-phase voltage source converter (VSC). The dynamic model of this renewable energy system is formulated and differential flatness properties are proven about it. To apply the proposed nonlinear optimal control, the state-space model of the PMLSG-VSC wave energy conversion unit undergoes an approximate linearization process at each sampling instance. The linearization procedure relies on a first-order Taylor-series expansion and involves the computation of the system’s Jacobian matrices. It takes place at each sampling interval around a temporary operating point, which is defined by the present value of the wave energy conversion unit’s state vector and by the last sampled value of the control inputs vector. An H-infinity feedback controller is designed for the linearized model of the wave energy conversion unit. To compute the feedback gains of this controller, an algebraic Riccati equation is repetitively solved at each time step of the control algorithm. The global stability properties of the control scheme are proven through Lyapunov analysis.

Optimal Planning of Urban Building-Type Integrated Energy Systems Considering Indoor Somatosensory Comfort and PV Consumption

Building energy consumption is the main urban energy consumption component, which mainly serves people-centered work and living energy demands. Based on the physical requirements of humans in urban buildings and to determine the comfortable body temperature in each season, this paper establishes a sizing optimization model of building-type integrated energy systems (IES) for sustainable development, where the cooling and heating loads required to maintain indoor somatosensory body comfort temperature are calculated. Depending on the external energy price, internal power balance, and other constraints, the model develops an optimal sizing and capacity-planning method of energy conversion and storage unit in a building-type IES with PV generation. The operating principle is described as follows: the PV generation is fully consumed, a gas engine satisfies the electric and thermal base load requirements, and the power system and a heat pump supply the remaining loads. The gas price, peak-valley electricity price gap, and heat-to-power ratio of gas engines are considered important factors for the overall techno-economic analysis. The developed method is applied to optimize the economic performance of building-type IES and verified by practical examples. The results show that using the complementary characteristics of different energy conversion units is important to the overall IES cost. A 300 kW building photovoltaic system can reduce the gas engine capacity from 936.7 kW to 854.7 kW, and the annual cost can be approximately reduced from 7.82 million to 7.50 million RMB yuan.

Guidelines for minimum cost transition planning to a 100% renewable multi-regional energy system

The paper deals with the energy transition, focusing on the decisions to be taken about the change in the energy conversion capacity of specified portion of the universe, such as industrial or domestic districts, regions, countries, etc. Conversion capacity is intended here as the set of all energy conversion and storage units characterized by type, size and number, and interacting with the natural gas and electricity grids. The goal is to find guidelines for new installations, obtained by simulations of a model able to describe properly the behavior of each energy conversion technology and the interaction with grids. The model is based on a traditional MILNP approach, but contains unique features in the literature, which allow to obtain results of general validity for applications to very different geographical areas, or to countries including very different regions that transmit energy with each other or export/import it from abroad. The main novelty of this work is to identify the best planning for the decarbonisation of energy demand sectors, according to the criterion of minimum cost, both at global and at regional level. The results applied to the case of Italy allow identifying clearly the energy demand sectors to which new installations should be applied first to minimize the cost for the total energy system, and the units that must be foreseen to satisfy these energy demands, i.e. a precise strategy for the energy transition towards a 100% renewable system.

The interaction between bucket number and performance of a Pelton turbine

The Pelton turbine is a type of hydraulic turbine suitable for medium, high and ultra-high head hydropower exploitation. As energy conversion units, the Pelton turbine has numerous design parameters affecting its energy conversion efficiency. In this paper, a three-dimensional unsteady simulation was conducted to analyze the influence of bucket number on the hydraulic performance and internal flow behavior of a model Pelton turbine. Five different bucket numbers in a total runner were selected for numerical examination, including the optimal number of 21 determined by the empirical formula. As the bucket number increased with the same operating conditions, the predicted hydraulic efficiency of the Pelton turbine rose to the maximum under optimal bucket number and then decline. Compared with the optimal bucket number of 21, the hydraulic efficiency of the Pelton turbine with 15, 17 buckets decreased by 2.8 % and 1 % respectively. By analyzing the variation of torque coefficient and water sheet flow under different bucket numbers, the interacting mechanism between bucket number and performance of the Pelton turbine was discussed. Numerical result indicated that the phase difference of the single bucket torque coefficient affected by the flow pattern exerted an influence on mean of the runner torque coefficient and hydraulic efficiency. This paper provides an in-depth understanding of the bucket number to the flow mechanism in the bucket for exploring the energy conversion efficiency of the Pelton turbine.

Optimized design and application performance analysis of heat recovery hybrid system for radioisotope thermophotovoltaic based on thermoelectric heat dissipation

Radioisotope thermophotovoltaic (RTPV) generators face a fundamental challenge, which is the significant output loss and energy wastage caused by the substantial thermal deposition resulting from the arrival of infrared radiation from the heat source at the energy conversion unit. This contradiction has gradually become a key limiting factor for its further development in recent years. In this work, a novel hybrid system based on the thermophotovoltaic-thermoelectric (TPV-TE) effect is proposed, in which the Bi2Te3-based I/W-type thermoelectric leg plays both heat dissipation and heat recovery for power supply. The heat recovery thermoelectric legs were prepared using a cold pressing mould and sintering method, and their Seebeck effect was used to convert the unwanted heat recover from InGaAs thermophotovoltaic cells into electrical power. The design preparation scheme of the heat recovery hybrid module and its potential application performance at 700–1000 K heat source temperature were investigated through experimental tests and simulations. The W-type TPV-TE heat recovery hybrid system exhibits good gain of 12.9% at 1000 K, and the output power can be increased by additional 21.6% in series mode. Simulations for environmental applications show better heat recovery in deep space than on Earth, with an output gain of 63.7% and an energy conversion efficiency of 11.23%. The heat recovery design enhances the competitiveness of the RTPV and provides new ideas for optimizing other heat recovery applications for thermal energy conversion systems.

Design and techno-economic analysis of a molten-salt driven energy conversion system for sustainable process heat supply

Storing off-peak cheap electricity from wind/solar farms for high-temperature heat storage in different mediums and using that for steam or high-temperature heat supply is a promising concept. A major issue for implementing high-temperature molten salt-based process heating systems is designing an appropriate heat exchanger system that can minimize the technical and operational risks and maximize the economic benefits. This study focuses on designing an optimal energy conversion unit based on this approach and conducts a techno-economic analysis of the developed system for a case study in Denmark to prove its proficiency. The system comprises a kettle boiler heat exchanger compatible with a high-temperature Sodium Hydroxide (NaOH) salt, and the case study is a cardboard factory demanding saturated steam at 10 bar, placed in the sustainable industrial business park GreenLab Skive. The results for the developed energy storage/conversion system with the given specifications and the salt are compared to an optimal design of the system when a conventional molten salt (solar salt mixture) is used. The results prove that the cost-effectiveness of the concept, in general, will be much dependent on the cost of charging electricity, and the system will only be promising if cheap off-grid electricity could be used during the whole charging process. It was found that the system with the benchmark salt NaOH for medium temperature use of ∼180 °C will be able to offer an LCOH of 67 €/MWh at an average cost of charging electricity of 63.6 €/MWh. The solar salt-cased energy conversion unit is less attractive economically but yet promising economically at cheap electricity charging rates.

Numerical modelling of a hydro-pneumatic energy storage system for smoothing power fluctuations from offshore wind

Energy storage systems are imperative in tackling the regulation of electricity supply and demand mismatch to avoid curtailment of wind energy. Co-locating energy storage in the same operating region as the offshore wind farms allows for an unobtrusive environment while also steering away from rising land prices. The presented work involves an offshore Hydro-Pneumatic Energy Storage (HPES) system made up of a subsea accumulator pre-charged with compressed air. The Energy Conversion Unit (ECU) of the system consists of a megawatt-scale hydraulic pump and a turbine. This paper discusses a novel numerical model developed in Python™ for simulating the operation of the ECU pump and turbine of the offshore HPES system by using a simple moving average, based on a time window of wind data, whilst also introducing a one-step-ahead forecasting model. The results of the research are split into two parts; Firstly, the analysis and validation of the Seasonal Auto Regressive Integrated Moving Average (SARIMA) forecasting model is performed. Secondly, results on the pump and turbine performance based on the smoothened power are shown. The research found that despite the centrifugal pump limitations due to variable head operation, a smoothened power output is efficiently (> 90 %) attained in retaining the intermittent power generated.

Risk-Oriented Operational Model for Fully Renewable Cooperative Prosumers in a Modern Water-Energy Nexus Structure

The day-by-day increment in the demand for diverse types of energy together with the CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based climate concerns has intensified the need for innovative decarbonization plans leading the energy sector to produce clean, cost-effective, and reliable multi-energy. Herein, inevitable water and power interactions unlock significant benefits for the integrated energy network in the form of water-energy nexus models. In this work, a holistic water-energy nexus model is developed for the operation of cooperative prosumers equipped with 100% renewables in the modern interconnected energy structure. The model is empowered by the transactive energy technology to allow prosumers to cooperatively share multi-energy with each other for reliably serving power and water in a deregulated environment. The proposed model also benefits from hydrogen-based energy conversion units that not only improve the flexibility of prosumers in reliable energy supply but also increase their economic achievements by selling the produced gas to the gas grid. As prosumers are targeted for fully clean energy production, their contributions in the energy interactions are under the high level of risks associated with renewables' intermittences. Due to this, a risk-averse stochastic operational model is proposed that enables the decision-maker to adopt optimal strategies against the uncertain fluctuations in the system. The effectiveness of the proposed model is examined considering prosumers located in Chicago, USA. According to the obtained results, the model can affordably facilitate the realization of Chicago's plans for achieving the goal of equipping with 100% renewable energy sources for a fully clean multi-energy generation.

Optimal decarbonization strategies for an industrial port area by using hydrogen as energy carrier

This article discusses possible strategies for decarbonizing the energy systems of an existing port. The approach consists in creating a complete superstructure that includes the use of renewable and fossil energy sources, the import or local production of hydrogen, vehicles and other equipment powered by Diesel, electricity or hydrogen and the associated refuelling and storage units. Two substructures are then identified, one including all these options, the other considering also the addition of the energy demand of an adjacent steel industry. The goal is to select from each of these two substructures the most cost-effective configurations for 2030 and 2050 that meet the emission targets for those years under different cost scenarios for the energy sources and conversion/storage units, obtained from the most reliable forecasts found in the literature. To this end, the minimum total cost of all the energy conversion and storage units plus the associated infrastructures is sought by setting up a Mixed Integer Linear Programming optimization problem, where integer variables handle the inclusion of the different generation and storage units and their activation in the operational phases. The comprehensive picture of possible solutions set allows identifying which options can most realistically be realized in the years to come in relation to the different assumed cost scenarios. Optimization results related to the scenario projected to 2030 indicate the key role played by Diesel hybrid and electric systems, while considering the most stringent, or much more stringent, scenarios for emissions in 2050, almost all vehicles energy demand and industry hydrogen demand is met by hydrogen imported as ammonia by ship.

Plant-wide byproduct gas distribution under uncertainty in iron and steel industry via quantile forecasting and robust optimization

In the modern iron and steel industry, the efficient distribution of byproduct gases faces significant challenges due to quantity- and quality-related uncertainties of gases. This study presents an optimal approach to gas distribution that addresses this issue by incorporating the energy flow network and the uncertain surplus gases from the manufacturing system. The uncertain optimization problem is formulated as a two-stage robust optimization (TSRO) model, including “here-and-now” decisions aimed at minimizing the start-stop cost of energy conversion units, as well as “wait-and-see” decisions aimed at minimizing the operating cost of gasholders and the penalties resulting from energy excess or shortage. To facilitate practical implementation, we propose a “first quantify, then optimize” approach: (1) quantifying the uncertainty of surplus gases via a conditional quantile regression (CDQ)-based T-step time series model, and (2) finding the optimal solution through a column-and-constraint generation algorithm. Furthermore, a case study is conducted on an industrial energy system to validate the proposed methodology. Computational results, using evaluation indicators, such as MAPE, RMSE, PICP, and PINAW, confirm the effectiveness of the data-driven time series model in accurately quantifying uncertainties in each period. Sensitivity analysis demonstrates that the proposed TSRO model achieves a favorable balance between robustness and flexibility by selecting the combination of “budget and quantile” and the parameters of storage and conversion units. Comparative results reveal: (1) the optimal objective of the TSRO closely aligns with that of stochastic programming (SP) and is 2.717 times higher than that of deterministic optimization (DO); and (2) the computation time of TSRO is 2.388 times longer than that of DO, yet significantly smaller than that of SP, being only 0.07 times longer. Consequently, TSRO can efficiently find a robust gas distribution solution with the desired level of conservativeness for integrated iron and steel plants.

Experimental study of a miniature organic Rankine cycle unit using ocean thermal energy

Miniature ocean thermal energy conversion (OTEC) unit is an attractive candidate for sustainable energy supply of autonomous ocean observation platforms. Due to the variability of power load, the OTEC remains susceptible to operation under off-design conditions. A miniature ORC-based OTEC unit was developed and constructed. The performance of the unit under design and off-design was experimentally examined. The effects of operating parameters (i.e., pump frequency and turbine frequency) on power generation and thermal efficiency were evaluate using response surface methodology. The results indicate that the unit can produce 0.917 kW net power with a thermal efficiency of 1.46% at 27 ℃ heat-source temperature and 6 ℃ cold-source temperature. Off-design steady-state assessment allows a wide operability range of working-fluid flow rate between 0.18 kg/s and 0.28 kg/s for R134a, corresponding to net power varying between −92 W and 166 W, as well as net thermal efficiency varying between −0.25% and 0.31%. Pump frequency is the primary operating variable affecting the unit performance, followed by turbine frequency. The optimal turbine frequency maximizing thermal efficiency increases with pump frequency, varying between 105 and 160 Hz. When the pump frequency is 32 Hz, the optimal turbine frequency is approximately 160 Hz, which corresponds to the maximum net output of 166 W. The current study offers experimental and theoretical supports for the design and operation of ORC-based OTEC unit.

AN INNOVATIVE WAVE ENERGY CONVERTER FOR MARINE DATA BUOY APPLICATIONS

A current research focus is on how to give steady and dependable power to offshore equipment with unique power needs, such as marine data platforms and buoys that are located far from the coast. Most of these gadgets currently make use of photovoltaic power generation, high- capacity batteries, and routinely replace electrical supply systems. Wave energy is being examined as a solution due to the significant reliance of photovoltaic power generation on solar radiation and the expensive cost associated with frequent battery replacements. Wave energy converters (WECs) are machinery that transform wave energy into electrical energy. Their main benefit is a steady supply of electricity. In this study, a brand-new integrated wave energy converter for marine data buoys is proposed and examined. It has great dependability and low maintenance costs. A magnetic lead screw (MLS)-based direct-drive energy conversion unit serves as its central component. To maximise its power production, the device can passively track the buoy' s pitching status as it is being affected by waves. Voltage, current, and power for marine data buoys were measured using specific data values that were depending on the turbulence. In order to improve the system's accuracy and decrease power dissipations, artificial neural networks (ANN) are used. Using the necessary power for the data buoy and the remaining energy stored in the electric battery to power another marine system INDEX TERMS: - Oscillating-body buoy, magnetic lead screw, and wave energy conversion.

Is Banning Fossil-Fueled Internal Combustion Engines the First Step in a Realistic Transition to a 100% RES Share?

Planning the best path for the energy system decarbonization is currently one of the issues of high global interest. At the European level, the recent policies dealing with the transportation sector have decided to ban the registration of light-duty vehicles powered by internal combustion engines fed by fossil fuels, from 2035. Regardless of the official positions, the major players (industries, politicians, economic and statistical institutions, etc.) manifest several opinions on this decision. In this paper, a mathematical model of a nation’s energy system is used to evaluate the economic impact of this decision. The model considers a superstructure that incorporates all energy conversion and storage units, including the entire transportation sector. A series of succeeding simulations was run and each of them was constrained to the achievement of the decarbonization level fixed, year by year, by the European community road-map. For each simulation, an optimization algorithm searches for a less costly global energy system, by including/excluding from the energy system the energy conversion units, storage devices, using a Mixed Integer Linear approach. Three optimization scenarios were considered: (1) a “free” scenario in which the only constraint applied to the model is the achievement of the scheduled decarbonization targets; (2) an “e-fuels” scenario, in which all new non-battery-electric light-duty vehicles allowed after 2035 must be fed with e-fuels; (3) a “pure electric” scenario, in which all new light-duty vehicles allowed after 2035 are battery-electric vehicles. The comparison of the optimum solutions for the three scenarios demonstrates that the less costly transition to a fully renewable energy system decarbonizes the transportation sector only when the share of renewable energy sources exceeds 90%. E-fueled light-duty vehicles always turn out to be a less expensive alternative than the electric vehicles, mainly because of the very high cost of the energy supply infrastructure needed to charge the batteries. Most of all, the costs imposed to society by the “e-fuels” and “pure electric” light-duty-vehicle decarbonizing scenarios exceed by 20% and 60%, respectively, the “free” transition scenario.

Numerical study on a nuclear-powered Stirling system for space power generation

The use of nuclear-powered Stirling systems for planetary and deep space exploration applications has drawn increasing attention in recent decades. As the critical energy conversion unit in the system, the free-piston Stirling engine (FPSE) is characterized by high efficiency, low mass, compact configuration, robustness, and long lifetime, but difficult to accurately model and analyze. A self-developed numerical model of the whole system, coupled with a third-order model of the FPSE, was proposed for the first time, and a nuclear-powered Stirling system comprising eight 1 kW FPSEs was designed. The methodology for designing a system with high efficiency, high specific power, and compact structure was proposed. Furthermore, the internal heat transfer and loss mechanisms were analyzed. The results revealed that the engines’ performance could be improved by increasing the temperature ratio of the hot end to the cold end. However, this leads to a corresponding increase in the size and mass of the heat exchangers. It was shown that the optimum hot-end temperatures for maximizing the system efficiency exist at different cold-end temperatures due to the radiation heat loss of heat pipes. When the hot-end and cold-end temperatures are respectively 1050 K and 450 K, a maximum system efficiency of 25.64% could be obtained. Moreover, the system efficiency and specific power could be increased by optimizing the FPSEs’ parameters and enhancing the heat exchangers’ heat transfer capabilities, and the adverse effect of the heat sink fluctuation could be inhibited accordingly. The distribution of the exergy losses changes greatly with the operating temperatures, and the primary parameter to be optimized also changes accordingly.

Development of an Educational Fuel Cell System for Mechanical Engineering Course

Although there is growth in electrochemical system applications such as batteries and fuel cells to power land and air transportation and the current push for hydrogen technology, modeling and control design of thermal and power aspects of such systems is not commonly taught. To incorporate such content, an educational learning hardware system with software interface had been constructed to teach process dynamics and control in selected undergraduate mechanical engineering courses. Given a fuel cell is an energy conversion unit that uses chemical fuel to produce electricity without combustion, a set of student groups developed an educational laboratory system that ensured reliable and consistent power delivery from fuel cell as well as stable hydrogen production using cost-effective and off-the-shelf resources. A 100W Proton Exchange Membrane Fuel Cell (PEMFC) system was constructed through integration of hardware components, and user software interface like MATLAB for accessibility and ease of use in a laboratory course setting. The interface accessed remotely or face-to-face allowed for flow rate, pressure, and temperature measurements to be recorded for student analysis related to understanding of thermal and power performance and management of fuel cell and/or electrolyzer at different operating conditions. The system performed well based on initial testing by a pilot group of other students. It will be implemented in an upcoming course offering related to energy conversion and/or thermal fluid laboratory.

A Numerical Model Comparison of the Energy Conversion Process for an Offshore Hydro-Pneumatic Energy Storage System

Energy storage is essential if net zero emissions are to be achieved. In fact, energy storage is a leading solution for reducing curtailment in an energy system that relies heavily on intermittent renewables. This paper presents a comparison between two numerical models which simulate the energy conversion unit performance of a hydro-pneumatic energy storage system. Numerical modelling is performed in PythonTM (Alpha Model) and Mathworks® Simulink® and SimscapeTM (Beta Model). The modelling aims to compare the time-series predictions for the simplified model (Alpha Model) with the more physically representative model (Beta Model). The Alpha Model provides a quasi-steady-state solution, while the Beta Model accounts for machinery inertias and friction within hydraulic flow circuits. Results show that the energy conversion performance simulations between the two models compare well, with a notable difference during system start-up due to the inclusion of transients in the Beta Model. Given its simplicity, the Alpha Model has high computational efficiency, while the Beta Model requires more computational time due to its complexity. This study showed that, despite its simplicity, the Alpha Model is able to generate results that are very similar to those from the Beta Model (with the average RMSE being less than 5%).