Thermodynamic Engine Research Articles

Learning analytics system to aid students in engineering thermodynamics: Impact of pre-requisite course attainment

Engineering thermodynamics is the core course of many majors, especially mechanical engineering and chemical engineering. Two groups of students from different majors and with different coefficients of difficulty of engineering thermodynamics examinations were selected for investigation. The students’ achievements for the three courses of mathematics, physics, and engineering thermodynamics were analysed, and the relationships between them were concluded. Investigation shows that college-level physics, especially physics 1, plays an important role in improving the study of engineering thermodynamics, and students with a poor physics knowledge foundation have difficulty obtaining scores above the average level in engineering thermodynamics. A strong advanced mathematics foundation is also important to get a good score in engineering thermodynamics. The relationships between the prerequisite courses investigated in this study and engineering thermodynamics are more evident when the engineering thermodynamics examination is difficult and are weak when the engineering thermodynamics examination is easy. Finally, based on the findings, a student learning advising system is proposed, and a feasible implementation method is presented.

Beating neat fuels by dedicated blending: Performance analysis of bio-hybrid fuel blends on a spark-ignition engine for passenger car applications

The alcohol fuel ethanol is well known for its favorable engine performance in terms of both high net indicated efficiency and low nitrogen oxide emissions. Other alternative neat fuels such as 2-butanone were not able to outperform ethanol in its engine performance. In addition, ethanol has lower production costs compared to 2-butanone, which makes ethanol even more attractive. To compete with neat fuels, model-based fuel design was introduced to tailor fuels by means of dedicated blending of neat alternative components. First, a blend consisting of ethanol, 2-butanone, cyclopentane, and cyclopentanone (EBCC) was defined. Second, a ketone–ester–alcohol–alkane (KEAA) blend consisting of methyl isopropyl ketone, methyl acetate, ethyl acetate, ethanol, methanol, and pentane was developed. Both blends were optimized regarding their production costs while simultaneously considering fuel properties such as the octane number, the oxygen content, and the enthalpy of vaporization. Although both blends showed promising fuel properties, their performance in an internal combustion engine was not evaluated in the fuel design process. This study presents investigations of both blends on a thermodynamic spark-ignition single-cylinder engine for passenger car applications with a compression ratio of 16.4. In particular, a variation of the engine load at an engine speed of 2000 1/min and two variations of the relative air/fuel ratio at the same engine speed and net indicated mean effective pressures of 6 bar and 15 bar were performed. The combustion behavior of the two blends was compared to that of neat ethanol, neat 2-butanone, and conventional gasoline pump fuel. In addition, 0D/1D simulations were performed to evaluate the efficiency losses during the combustion. EBCC achieved a maximum net indicated efficiency of 46.9% at a net indicated mean effective pressure of 15 bar and a relative air/fuel ratio of 1.7, exceeding ethanol’s maximum net indicated efficiency of 46.0% in the same operating point. KEAA achieved a lower net indicated efficiency than ethanol and was on the same level as neat 2-butanone, resulting in a maximum net indicated efficiency of 45.0% in the same operating point. This work shows that the combustion performance in an internal combustion engine should be considered in the fuel design process to better predict promising fuel candidates from an engine perspective.

A numerical evaluation and guideline for thermal barrier coatings on gasoline compression ignition engines

The application of thermal barrier coatings (TBCs) for internal combustion engines has drawn more research attention in recent years due to the improved coating technology and advanced material properties. This paper presents the combination of thermal barrier coatings with an advanced combustion concept: gasoline compression ignition (GCI). This study aims to evaluate the coating performance with GCI combustion on Aramco’s light-duty GCI engine. The thermodynamic engine model has been established and collaborated with CFD results to investigate thermal barrier coatings for GCI with a PPCI-diffusion combustion strategy primarily at a load of 23.5 bar IMEPg. Two real-world coating materials were pre-selected as Gen.1 and Gen.2 candidates. The investigation consists of three main topics: the effect of coating thickness on GCI, the effect of intake boost on the performance of traditional coatings and temperature swing coatings, and the effect of combustion chamber coverage on engine performance. The result shows that the TBC thickness became the key parameter to optimize for TBC with GCI combustion mode, and in the end, 250–500 microns is recommended based on the temperature limit of ceramic material. It was also found that the high level of intake boosting could significantly alleviate the charge heating penalty. The coverage of piston, engine head, and both intake and exhaust valves should be applied to achieve the highest efficiency gains. It was found that the gain ratio from each chamber component can be drastically different at different loads.

Feasibility analysis of a thermo-hydraulic process for reverse osmosis desalination: Experimental approach

Reverse osmosis is a widely used desalination technique, mainly because of its low specific energy consumption. Autonomous reverse osmosis processes are increasingly developed because of their energy efficiency and the decentralization of numerous water stress areas. In this context, a reverse osmosis process powered by an innovative thermo-hydraulic desalination system using heat has been developed. This new process aims to autonomously produce fresh water from a brackish water source, compatible with the needs of a small remote village. This new reverse osmosis desalination process exploits a low temperature heat source (60–80 °C) such as the one delivered by solar flat-plate collectors. The heat is then converted into hydraulic energy by a thermodynamic engine cycle in which the expansion of the working fluid directly pressurizes the brackish water by means of hydro-pneumatic tanks, while energy from high pressure brine is recovered by an innovative hydraulic cylinder. Since previous numerical work on this process shown a specific energy consumption about 12 kWh m−3 for a 4 g L−1 brackish water, which is close to performances of relatable processes, an experimental full scale prototype has been built. The work presented here shows the results of the experiments conducted on this prototype, its behavior and performances. Numerical and experimental results are compared and discussed, and confirm the feasibility of the process. These tests show a promising cyclic functioning as the numerical results suggested. The freshwater production and salinity is remaining under the drinkability limit and the experimental specific energy consumption has been calculated to 25 kWh m−3. In order to reach better performances, transfer tanks needs to be improved to avoid heat transfer between working fluid and saltwater which leads to condensation issues, and another hydraulic cylinder design needs to be consider to avoid gasket abrasion.

Thermodynamic engine powered by anisotropic fluctuations

The purpose of this paper is to present the concept of an autonomous Stirling-like engine powered by anisotropy of thermodynamic fluctuations. Specifically, simultaneous contact of a thermodynamic system with two heat baths along coupled degrees of freedom generates torque and circulatory currents---an arrangement referred to as a Brownian gyrator. The embodiment that constitutes the engine includes an inertial wheel to sustain rotary motion and average out the generated fluctuating torque, ultimately delivering power to an external load. We detail an electrical model for such an engine that consists of two resistors in different temperatures and three reactive elements in the form of variable capacitors. The resistors generate Johnson-Nyquist current fluctuations that power the engine, while the capacitors generate driving forces via a coupling of their dielectric material with the inertial wheel. A proof-of-concept is established via stability analysis to ensure the existence of a stable periodic orbit generating sustained power output. We conclude by drawing a connection to the dynamics of a damped pendulum with constant torque and to those of a macroscopic Stirling engine. The sought insights aim at nanoengines and biological processes that are similarly powered by anisotropy in temperature and chemical potentials.

On the operational characteristics and economic value of pumped thermal energy storage

Pumped thermal energy storage (PTES) systems use an electrically-driven heat pump to store electricity in the form of thermal energy, and subsequently dispatch the stored thermal energy to generate electricity using a thermodynamic heat engine. Optimal day-ahead operational scheduling and annual value of a PTES system based on Joule–Brayton thermodynamic cycles and two-tank molten salt hot thermal storage is evaluated in this paper. Production cost models, which simultaneously optimize commitment and dispatch schedules for an entire set of generators to minimize the cost of satisfying electricity demand, are employed to determine system-optimal operation and day-ahead energy value of the PTES system within each of six hypothetical near-future grid scenarios intended to approximately represent the U.S. Western Interconnection or the Texas Interconnection. Sensitivity to grid scenario (including the contribution of variable renewable energy sources), thermal storage capacity, relative heat pump and heat engine capacities, and startup/shutdown cycling costs are evaluated. PTES energy value and heat engine annual capacity factor increase strongly as the contribution of variable renewable resources increases, heat pump capacity increases relative to heat engine capacity, or PTES cycling costs decrease. Grid scenarios in which the contribution of variable renewable energy is dominated by solar photovoltaics (PV) vs. wind produce inherently different PTES operational patterns. Annual PTES energy value within PV-dominated scenarios increased with storage capacity only up to approximately seven hours of full-load discharge capacity, whereas that within wind-dominated scenarios exhibited a continual increase with storage duration up to at least 16 hours.

Beating Carnot efficiency with periodically driven chiral conductors.

Classically, the power generated by an ideal thermal machine cannot be larger than the Carnot limit. This profound result is rooted in the second law of thermodynamics. A hot question is whether this bound is still valid for microengines operating far from equilibrium. Here, we demonstrate that a quantum chiral conductor driven by AC voltage can indeed work with efficiencies much larger than the Carnot bound. The system also extracts work from common temperature baths, violating Kelvin-Planck statement. Nonetheless, with the proper definition, entropy production is always positive and the second law is preserved. The crucial ingredients to obtain efficiencies beyond the Carnot limit are: i) irreversible entropy production by the photoassisted excitation processes due to the AC field and ii) absence of power injection thanks to chirality. Our results are relevant in view of recent developments that use small conductors to test the fundamental limits of thermodynamic engines.

Thermodynamics of Power–Maxwell charged AdS black holes with quintessence in Rastall gravity: Heat engine

In this paper, we derive thermodynamic quantities of Power–Maxwell charged black holes, in the presence of quintessence in Rastall gravity and discuss further about the [Formula: see text]–[Formula: see text] criticality and stability and how these quantities depend on various parameters. Then we show that the said black hole can be thought of as a thermodynamic heat engine and we analyze the efficiency for Carnot cycle and Rankin cycle.

Thermo-fluid dynamic resonance in cancer cells

In the third decade of XX century, Warburg pointed out that cancer cells follow a fermentative respiration process, as a consequence of a metabolic injury. In this paper, we consider this statement in the following way: any cell process requires energy, so, in the cell, a control of the energy conversion can represent a possible control of the cell processes. Engineering thermodynamics is the science that studies the conversion of energy into work. So, thermodynamics could represent a powerful approach to analyse of the energy conversion in the biosystems, for their control. Cells regulate their metabolisms by energy and mass (ions included) flows, and the heat flux occurs by the convective interaction with their environment. Here, we consider fluxes through the biosystems border, their shapes and the characteristic time of thermal interaction with the blood and water, in the cell environment. Moreover, just in relation to time, it is possible to consider the resonance phenomena. Resonance forces natural behaviours of systems, when a wave of a frequency, related to the characteristic time, income to a system. Here, we introduce the biothermodynamic characteristic frequency, which is the characteristic frequency of a biosystem, evaluated by a thermo-fluid dynamic approach, in order to control the fluxes through the cancer membrane, and to force it towards an optimal behaviour, by changing the concentrations of ions, inside and outside of the membrane itself. The result consists in a control of the cellular metabolic processes, and also of the energy available to cancer, for its growth. In this way, the cancer growth rate can be reduced.

On the Relation Between Information and Power in Stochastic Thermodynamic Engines

The common saying, that information is power, takes a rigorous form in stochastic thermodynamics, where a quantitative equivalence between the two helps explain the paradox of Maxwell's demon in its ability to reduce entropy. In this letter, we build on earlier work on the interplay between the relative cost and benefits of information in producing work in cyclic operation of thermodynamic engines (by Sandberg et al. 2014). Specifically, we study the general case of overdamped particles in a time-varying potential (control action) in feedback that utilizes continuous measurements (nonlinear filtering) of a thermodynamic ensemble, to produce suitable adaptations of the second law of thermodynamics that involve information.

Application of Basic Knowledge of Physical Chemistry in Chemical Engineering Thermodynamics Teaching

Application of Basic Knowledge of Physical Chemistry in Chemical Engineering Thermodynamics Teaching

Simulation Modeling of a Ship Propulsion System in Waves for Control Purposes

The article deals with a simulation approach to the representation of the ship motions in waves, interacting with the propulsion system behavior (diesel engine and propeller). The final goal is the development of a simulator, as complete as possible, that allows the analysis of the main engine thermodynamics in different sea conditions, also in the unfavorable event of dynamic instability of the hull, and the correct management of the other propulsion components. This latter aspect is particularly interesting in some of the last new energy solutions for decarbonization of ships, concerning, for example, auxiliary electric motors, powered by batteries, to support the traditional diesel-mechanical propulsion (especially in heavy weather conditions). From this point of view, a proper analysis of the engine dynamic performance, affected by particular sea states, is fundamental for a smart management and control of shaft generators/auxiliary electric motors, batteries, etc. To this end, the work presents and highlights the main features of a ship simulator, suitable for the study of the new propulsion solutions that are emerging in maritime transport. Some representative results will point out the complex non-linear behavior of the propulsion plant in waves. Moreover, a parametric roll scenario will be investigated, in order to highlight the capability of the conceived simulator in modeling the effects of the dynamic instability of the hull on the propulsion plant.

Thermal resonance in living cells to control their heat exchange: Possible applications in cancer treatment

In the end of the second decade of 20th century, Warburg showed how cancer cells present a fermentative respiration process, related to a metabolic injury. Here, an analysis of the cell process is developed, based on its heat outflow, in order to control cancer progression. Engineering thermodynamics represents a powerful approach to develop this analysis. Indeed, the Engineering thermodynamic methods are introduced to analyse the bio-systems, in relation to heat outflow, in order to control this flux. Cells regulate their metabolisms by energy and ion flows, and the heat flux is controlled by the convective interaction with their environment. The bio-thermodynamic characteristic frequency is introduced and it is evaluated by a classical heat transfer approach. Resonance forces natural behaviours of systems, and, here, it is introduced to control both the fluxes, through the cancer membrane, and the cellular metabolic processes. Consequently, the energy available to cancer, for its growth, is controlled, too. The result, experimentally proven, consists in the decrease of rate of cancer growth.

Understanding and Correlating of Chemical Engineering Thermodynamics I and Process Heat Transfer through Integrated Project

The development of engineering education plays a significant role in creating a competency base for engineering students to be excellent in engineering practice as well as other professional skills such as communication, teamwork and leadership. Project-Based Learning via Integrated Project entitled Heat Recovery from Ammonia Synthesis Reactor for Power Generation was introduced as a new learning approach for First Year First Semester Chemical Engineering student to replace the conventional learning approach via lecture. This integrated project is a hybrid of two core Chemical Engineering subjects for First Year students: Chemical Engineering Thermodynamics I and Process Heat Transfer. This integrated project aims to evaluate students' ability to relate two different subjects when learning in the same semester and apply them to the same application. This integrated project is expected to enhance students' learning curve and ensure that the output of this study can be achieved in a consistent effort and timely manner. Assessments in the form of formative (reflection and peer review) and summative (final report) are applied to the students via individual and group. Based on the reflection's analysis, 50% of the students mentioned that the project is very challenging; meanwhile, only 30% agreed that they could relate the project with both subjects even though it is complex and challenging. Despite that, 70% of the students stated that their learning goal is achievable. They were able to view the industrial application, especially the heat exchanger application, through this project. Overall, 90% agreed that they achieved this integrated project's objectives: to relate two different subjects when learning in the same semester and apply them to the same application. Hence, it is noteworthy to highlight that this integrated project is carefully mapped. The new learning approach via Project-Based Learning brought positive outcome towards the students' learning experiences, skills and understanding.

Principle of least effort vs. maximum efficiency: deriving Zipf-Pareto's laws

This paper provides a derivation of Zipf-Pareto laws directly from the principle of least effort. A probabilistic functional of efficiency is introduced as the consequence of an extension of the nonadditivity of the efficiency of thermodynamic engine to a large number of living agents assimilated to engines, all randomly distributed over their output. Application of the maximum calculus to this efficiency yields the Zipf's and Pareto's laws.

Economic Cycles of Carnot Type.

Originally, the Carnot cycle was a theoretical thermodynamic cycle that provided an upper limit on the efficiency that any classical thermodynamic engine can achieve during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference by the application of work to the system. The first aim of this paper is to introduce and study the economic Carnot cycles concerning Roegenian economics, using our thermodynamic–economic dictionary. These cycles are described in both a diagram and a diagram. An economic Carnot cycle has a maximum efficiency for a reversible economic “engine”. Three problems together with their solutions clarify the meaning of the economic Carnot cycle, in our context. Then we transform the ideal gas theory into the ideal income theory. The second aim is to analyze the economic Van der Waals equation, showing that the diffeomorphic-invariant information about the Van der Waals surface can be obtained by examining a cuspidal potential.

Plasma electrolytic oxidation thermal barrier coating for reduced heat losses in IC engines

The work involved the development and on-engine testing of a new “thermo-swing” barrier coating for reduced wall heat transfer and increased thermal efficiency in future diesel engines utilizing aluminium alloy pistons. Such swing coatings, of low thermal conductivity and low specific heat capacity, have recently been proposed to produce a dynamic thermal barrier layer that rapidly changes the temperature of the upper surface of the piston crown in response to the adjacent in-cylinder gas temperature. The new coating tested in this work was formed directly from the piston substrate material using an optimised plasma electrolytic oxidation process, with a silica top coat subsequently applied to entrap air within coating pores. Benchtop laser flash measurements were undertaken to quantify coating thermal properties and provide the required empirical data for future thermal simulation. Coatings of varying features were tested in a bespoke thermodynamic single cylinder diesel engine instrumented for precision measurements of in-cylinder pressure, fuel consumption and legislated engine-out emissions. The optimum coating applied across the full piston crown and bowl enabled up to 3% improvement in indicated thermal efficiency under idealised part load operating conditions. The coating reduced heat transfer during combustion, leading to elevated engine-out NOx. By retarding combustion phasing slightly from the optimum, the NOx increase could be mitigated while still retaining most of the fuel consumption benefit, with the remaining benefit associated with reduced heat transfer during the remaining power stroke. The emissions of other key pollutants (CO, unburned hydrocarbons and soot) were less affected under the part load conditions tested.

Integrated Project as Innovative Assessment to Enhance Learning Experience in Thermodynamics Class

An integrated project is introduced to students to relate the concepts and equations taught between courses in the same semester. It also helps students in managing allocated time for assessments and collaborating among them, which eventually enhances their learning experience, especially for thermodynamics courses. In this case, the integrated project was done by relating two courses: Chemical Engineering Thermodynamics 2 and Separation Process 1 for Year 2 students. The methanol production plant was chosen as a model case, where students need to simulate the vapor/liquid equilibrium in the purification unit using HYSYS simulation software. Overall, students show highly positive sentiments upon the projects, in which more than 90% of them think that the project helps them to understand the coursework materials and prepare for other assessments. The majority of students want to experience the same type of project in the future, and it helps to save their time rather than working on separate projects. The project also exposes the students to set skills related to technical competence and soft skills that could build their characters.

Multilevel quantum thermodynamic swap engines

We study energetic exchanges and fluctuations in two-stroke quantum thermodynamic engines where the working fluid is represented by two multilevel quantum systems, i.e. qudits, the heat flow is allowed by relaxation with two thermal reservoirs at different temperatures, and the work exchange is operated by a partial-swap unitary interaction. We identify three regimes of operation (heat engine, refrigerator, and thermal accelerator), present the thermodynamic uncertainty relations between the entropy production and the signal-to-noise ratio of work and heat, and derive the full joint probability of the stochastic work and heat. Our results bridge the gap between two-qubit and two-mode bosonic swap engines, and show which properties are maintained (e.g., a non fluctuating Otto efficiency) and which are lost for increasing dimension (e.g., small violations of the standard thermodynamic uncertainty relations or the possibility of beating the Curzon-Ahlborn efficiency).

Synergies between aliphatic bio-alcohols and thermo-chemical waste heat recovery for reduced CO2 emissions in vehicles

The impact of aliphatic (C1–C5) bio-alcohols for on-board thermo-chemical exhaust waste heat recovery, H2 production and hence fuel savings for a gasoline direct injection (GDI) engine has been investigated with iso-octane as reference. Gibbs free energy analysis was conducted to establish which reaction pathways for fuel reforming were dominant and how these reactions are influencing H2 and CO yield. To obtain engine exhaust temperature and mass flow maps for several steady-state engine operation conditions, an engine model was created in AVL CRUISE M and validated with real GDI engine data. A methodology was developed to couple the thermodynamic reactor results and engine model results to compute waste exhaust heat recovery by accounting limited available exergy in exhaust and optimising reforming reactor’s operational parameters to maximise exergy recovery and reforming efficiency in the reformer. Under steady state engine operation, iso-pentanol was more effective overall due to its high hydrogen content by weight (8.3% and 4.3% higher than methanol and ethanol respectively), high energy density of 34.6 MJ/kg (42.2%, 22.3% 13.2% and 4.3% higher than C1-C4 alcohols respectively), high reforming endothermicity and the versatility for heat recovery under all engine operation conditions with heat recovery of at-least 2% of engine power even under low-load conditions.Subsequently, the engine model was evolved into a full AVL CRUISE M vehicle model and was studied over a duty-cycle to evaluate the fuels further. Iso-pentanol and iso-propanol were most effective concerning average heat recovery over the duty cycle. For the high-speed regions of the cycle, up-to 9% of waste heat recovery is observed for C4 and C5 bio-alcohols. In terms of vehicle’s carbon emissions, iso-pentanol, n-butanol, and ethanol exhibited maximum CO2 reduction of 8.4%, 7.7% and 7.1% respectively. The results presented herein indicates versatility of bio-alcohols for cleaner and more efficient powertrains.