This work assesses if a plausible theoretical thermo-chemical scheme can be conceived of, that is capable of extracting work from chemical reactants which can be compared with work produced by a fuel cell, when both processes are supplied with the same reactants. A theoretical process is developed to convert heat liberated from a chemical reaction to work. The hypothetical process is carried over a series of isothermal chemical reactor - heat engine combinations. Conducting the chemical reaction and work extraction over a series of temperature steps minimizes irreversibilities that result from the chemical reaction and heat transfer. Results obtained from the numerical calculations on the scheme confirm that when a large number of reactors-engine combinations are used, irreversibility of the proposed hypothetical reactor-engine combination can be reduced to zero. It is concluded from the results, that the theoretical model is as efficient as a fuel cell when both have the same chemical reaction under identical conditions. The effect of inert gas chemistry on the process has also been observed. It is determined from the results that the chemistry of the inert gas does not affect the proposed process. It is determined from results of a parametric study on the composition of inert gas, that the reduction of inert gas does not significantly improve the efficiency of the proposed process.

This work assesses if a plausible theoretical thermo-chemical scheme can be conceived of, that is capable of extracting work from chemical reactants which can be compared with work produced by a fuel cell, when both processes are supplied with the same reactants. A theoretical process is developed to convert heat liberated from a chemical reaction to work. The hypothetical process is carried over a series of isothermal chemical reactor - heat engine combinations. Conducting the chemical reaction and work extraction over a series of temperature steps minimizes irreversibilities that result from the chemical reaction and heat transfer. Results obtained from the numerical calculations on the scheme confirm that when a large number of reactors-engine combinations are used, irreversibility of the proposed hypothetical reactor-engine combination can be reduced to zero. It is concluded from the results, that the theoretical model is as efficient as a fuel cell when both have the same chemical reaction under identical conditions. The effect of inert gas chemistry on the process has also been observed. It is determined from the results that the chemistry of the inert gas does not affect the proposed process. It is determined from results of a parametric study on the composition of inert gas, that the reduction of inert gas does not significantly improve the efficiency of the proposed process.

No description available.

The invention of shape memory alloys spurred a period of intense interest in the area of heat engines in the late 70's and early 80's. It was believed that these engines could use heat from low temperature sources such as solar heated water, geothermal hot water and rejected heat from conventional engines as a significant source of power. The interest has since dwindled, largely because small prototype devices developed in the laboratory could not be scaled up to produce significant power. It is believed that the scaled-up designs failed because they were dependent on friction as the driving mechanism, which led to large energy losses and slip. This thesis proposes a new chain and sprocket driving mechanism that is independent of friction and should therefore allow for large-scale power generation. This thesis begins by presenting properties and applications of shape memory alloys. The proposed design is then described in detail, followed by a review of the evolution that led to the final design. A brief chapter on thermodynamic modeling and a summary chapter suggesting improvements on the current design follow. / Master of Science

This work presents a novel approach to arranging shape memory alloy (SMA) wires into a functional heat engine. Significant contributions include the design itself, a preliminary analytical model and the realization of a research prototype; thereby, laying a foundation from which to base refinements and seek practical applications. Shape memory alloys are metallic materials that, if deformed when cold, can forcefully recover their original, "memorized" shapes, when heated. The proposed engine consists of a set of SMA wires stretched between two crankshafts, synchronized to rotate in the same direction. Cranks on the first crankshaft are slightly longer than cranks on the second. During operation, the engine is positioned between two distinct thermal reservoirs such that half of its wires are heated while the other half are cooled. Wires on the hot side attempt to contract, driving the engine in the direction that relieves the heat-induced stress. Wires on the cold side soften and stretch as the engine rotates. Because the force generated during heated recovery exceeds that required for cooled deformation, the engine is capable of generating shaft power. Limited experimental measurements of shaft speed were performed. An analytical model of the engine predicts that the maximum output power for the prototype, under test conditions, should be 0.75 W. Thermal efficiency, though not measured or calculated in this work, is expected to be low. Potential applications may include the conversion of waste heat into shaft power. / Master of Science

The Marnoch heat engine (MHE) is a new type of heat engine currently under development at the University of Ontario Institute of Technology. The MHE can use waste or collected heat at temperatures that are currently unusable or not eco- nomically viable to use by conventional technologies. The MHE operates by using a heat source to heat the air in one heat exchanger and cool the air in another. This creates a pressure di erence. This pressure di erence drives a two-way piston connected to a ywheel. A generator connected to the ywheel converts the me- chanical energy of the ywheel into electricity. This thesis presents a simulation of the current MHE prototype. The simulation is designed to be easily customized to allow it to model the performance of future possible MHE installations and predict their performance. The simulation is shown to accurately model the performance of the MHE prototype by running under conditions similar to those found in the lab, and comparing its results to collected data from the prototype. Simulations were also run to show the model's ability to model possible applications with di erent operating conditions and physical components. / UOIT

The Marnoch Heat Engine (MHE) is a recently patented type of new heat engine that produces electricity from lower temperature heat sources. The MHE utilizes lower temperature differences to generate electricity than any currently available conventional technologies. Heat can be recovered from a variety of sources to generate electricity, i.e., waste heat from thermal power plants, geothermal, or solar energy. This thesis examines the performance of an MHE demonstration unit, which uses air and a pneumatic piston assembly to convert mechanical flow work from pressure differences to electricity. This thesis finds that heat exchangers and the piston assembly do not need to be co-located, which allows benefits of positioning the heat exchangers in various configurations. This thesis presents a laboratory-scale, proof-of-concept device, which has been built and tested at the University of Ontario Institute of Technology, Canada. It also presents a thermodynamic analysis of the current system. Based on the MHE results, component modifications are made to improve the thermal performance and efficiency. The current configuration has an efficiency of about thirty percent of the maximum efficiency of a Carnot heat engine operating in the temperature range of 0oC to 100oC. The analysis and experimental studies allow future scale-up of the MHE into a pre-commercial facility for larger scale production of electricity from waste heat. / UOIT

No description available.

Thermomagnetic motors can represent an alternative for the conversion of heat into mechanical energy, limited by the critical transition temperature (TC) of the used magnetic materials. Thus, by using materials with a TC close to room temperature, the energy available in the form of low-grade heat sources can be converted into useful mechanical work. This thesis proposes the development of a thermomagnetic motor to be operated with heat sources at temperatures in the range from 343 to 353 K, and a heat sink at room temperature, using water as the heat transfer fluid, presenting a novel approach to the construction of thermomagnetic devices. The design of this thermomagnetic motor was developed with the intent of producing a rotary movement, working similarly to an electric stepper motor, where instead of the electromagnetic coils being activated by an electric current, plates of a magnetic material change their magnetization state, due to a change in their temperature caused by the heat transfer with the heat transfer fluid. The analysis of the thermomagnetic motor proposed was done with the adoption of an integrated approach of numerical simulation and experimental validation. The evaluation of the motor is divided into the three main physical phenomena it encompasses: the magnetic field source, the heat transfer processes involved in the change of temperature of the magnetic material, and the system dynamics and power production. Each of these systems was modeled using computational tools. These models were then validated according to the data measured, obtained from a test stand of an idealized thermomagnetic motor, and for a rotary thermomagnetic motor. This methodology allowed a more comprehensive understanding of the critical working principles of the motor developed, and with that a fast advancement of the technology through a validated computational model. The computational models helped to identify the critical components to be improved in the development of these motors. These parameters can be guidelines for the design of thermomagnetic motors. One of the ways identified to produce a significant performance improvement, in the simulations, was the adoption of a control strategy that promotes the regeneration of heat in the plates of magnetic material, through which an improvement in the efficiency of 2.7 times could be achieved. / Motores termomagnéticos representam uma alternativa para a conversão de calor em energia mecânica, limitada apenas pela temperatura crítica da transição termomagnética (TC) dos materiais magnéticos. Ao usar materiais com TC próximo à temperatura ambiente, pode-se realizar a conversão da energia contida nas chamadas fontes pobres de calor, produzindo trabalho mecânico útil. Esta tese propõe o desenvolvimento de um motor termomagnético para operação com fontes de calor com temperaturas entre 343 e 353 K, e resfriamento à temperatura ambiente, utilizando a água como fluído de troca térmica, apresentando uma abordagem inovadora para dispositivos termomagnéticos. O motor foi projetado para produção de movimento rotativo de um eixo, per meio de um princípio similar ao de um motor de passo, no qual em vez de bobinas ativadas pela passagem de corrente elétrica, placas de material magnético sofrem uma mudança em seu estado de magnetização, devido à mudança de temperatura, causada pela troca de calor com a água. A análise do motor termomagnético proposto foi realizada com a adoção de uma abordagem integrada de simulações numéricas e validação experimental, dividindo a avaliação dos motores nos três principais fenômenos físicos envolvidos em seu funcionamento: a fonte de campo magnético, o processo de troca térmica envolvido na mudança de temperatura do material magnético, a dinâmica do sistema e produção de potência. Cada um destes sistemas foi modelado usando ferramentas computacionais. Os resultados obtidos foram então validados utilizando dados experimentais, obtidos a partir da construção e caracterização de uma bancada de testes para um motor termomagnético idealizado, e também para o motor termomagnético rotativo construído. Esta metodologia propiciou maior entendimento das funções críticas do motor desenvolvido, e possibilitou ainda sua otimização, através do estudo dos modelos computacionais validados. Os parâmetros obtidos ajudaram a identificar componentes críticos para melhoria no projeto do motor rotativo construído, e servem também como guias gerais para projetos de motores termomagnéticos. Um dos componentes com elevado potencial de melhoria foi a adoção de uma estratégia de controle para a regeneração do calor nas placas de material magnético, o que possibilitou, nas simulações, uma melhoria até 2,7 vezes na eficiência.

Since the realisation of the computer, and shortly after the inception of artificial intelligence (AI), there has been an explosion of research solving human-level tasks using autonomous entities that are able to learn about an environment by observing and influencing it, known as intelligent agents (IA). This potent AI technique has yet to filter into the field of thermoscience, where the conceptual design and optimisation of complex energy systems has been a particularly challenging problem. Much of the design process still requires human expertise. But with the continual increase in computational power and the use of IAs, it is now time to shift the responsibility from the human to the computer. This research attempts to answer the question of whether it is possible for a computer to conceptually design a complex energy system autonomously, from inception. The complex energy system to be designed and optimised is a thermoacoustic heat engine (TAHE), which converts thermal to acoustic power. The complexity of its physical behaviour and its many design parameters makes it a challenging energy system for conceptual design and optimisation and consequently an ideal candidate for this particular research. The TAHE is designed for low temperature waste heat utilisation from a baking process. In this work an approach is employed that is based on a reinforcement learning intelligent agent (RLIA). The RLIA is first employed to simultaneously optimise thirteen design parameter values. The RLIA was able to learn key design features of a TAHE which lead to the reduction in acoustic losses and an acoustic power from the engine of 495.32 W, when the thermal power input was 19 kW. For the main experiment, the RLIA must conceptually design the TAHE from scratch, changing both the parameter values and the configuration of the device. The results have shown the remarkable ability of the RLIA to identify several key design features of the TAHE: the correct configuration of the device, selecting designs that reduce acoustic losses, create positive acoustic power in the stack region and determine the region of optimality of the design parameter values. The RLIA has shown a great capacity to learn, even when contending with a complex environment and a vast search space. With this work we have introduced RLIAs as a new way approach to such multidimensional problems in the field of thermoscience/thermal engineering.