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Abstract Ammonia-based chemisorption cycle driven by low grade heat exhibits vast potential for power generation because there exists huge pressure difference between the two salt-adsorbent-filled reactors. However, the intrinsic feature of ammonia as a wet fluid and the difficult match between chemisorption cycle and expansion device impede the development of such a power generation system and also increase the difficulty of practical implementation. To explore maximum benefits of this technology, the present work has proposed and studied a new resorption power generation cycle that applies multiple expansion. The application of multiple expansion integrated with reheating processes aims to overcome the limitation of the ammonia being wet fluid and fully harness the huge pressure difference that chemisorption can offer for power generation, leading to the improvement of energy efficiency. The performance of the proposed multiple expansion resorption power generation cycle using three typical resorption salt pairs, including sodium bromide – manganese chloride, strontium chloride – manganese chloride and sodium bromide – strontium chloride, have been investigated not just based on theoretical thermodynamics but also with the consideration of practical factors to obtain better understanding and more insights for a real system design. The multiple expansion resorption power generation using sodium bromide – manganese chloride and sodium bromide – strontium chloride pairs can achieve 100–600 kJ/kg (ammonia) work output when heat source temperature is from 30 °C to 150 °C; the multiple expansion using strontium chloride – manganese chloride pair has higher average work output per one expansion stage than that using the other two pairs. The cyclic energy efficiency can be achieved as 0.06–0.15 when implementing 2–4 expansions in a more practical scenario where the equilibrium pressure drop is set to 2 bar and the heat source temperature is in the range of 80–150 °C. Such efficiencies are circa 27–62% of Carnot efficiency under the same thermal conditions.

Abstract System-level dynamic models of power plants are valuable tools for the assessment and prediction of plant performance, decisions on the design configuration, and the tuning of operating procedures and control strategies. In this work, the development of an integrated power plant model is presented. This model is validated against steady-state data from a subcritical power plant with reheat and regenerative cycles. The coal-fired power plant model studied has nominal power generation of 605 MW and efficiency of 38.3%. Traditional, regulatory control architectures are incorporated into and tuned with the dynamic power plant model. Dynamic simulation shows that the plant model is stable for sudden changes in coal load, and the controllers are able to maintain the controlled variables at their set points. In this two-part publication, we present the complete workflow of data collection, model development and validation, control tuning, dynamic optimization formulation and solution, and supervisory control architecture for a coal-fired subcritical power plant. Part I focuses on elements of model development and analysis, illustrating the advantages of acausal, object-oriented modeling in power plant simulation. Part II illustrates the use of this model for efficiency optimization under transient part-load operation.

Abstract Liquid fuels are likely to remain the main energy source in long-range transportation and aviation for several decades. To reduce our dependence on fossil fuels, liquid biofuels can be blended to fossil fuels – or used purely. In this paper, coconut methyl ester, standard diesel fuel (EN590:2017), and their blends were investigated in 25 V/V% steps. A novel turbulent combustion chamber was developed to facilitate combustion in a large volume that leads to ultra-low emissions. The combustion power of the swirl burner was 13.3 kW, and the air-to-fuel equivalence ratio was 1.25. Two parameters, combustion air preheating temperature and atomizing air pressure were adjusted in the range of 150–350 °C and 0.3–0.9 bar, respectively. Both straight and lifted flames were observed. The closed, atmospheric combustion chamber resulted in CO emission below 10 ppm in the majority of the cases. NO emission varied between 60 and 183 ppm at straight flame cases and decreased below 20 ppm when the flame was lifted since the combustion occurred in a large volume. This operation mode fulfills the 2015/2193/EU directive for gas combustion by 25%, which is twice as strict as liquid fuel combustion regulations. The 90% NO emission reduction was also concluded when compared to a lean premixed prevaporized burner under similar conditions. This favorable operation mode was named as Mixture Temperature-Controlled (MTC) Combustion. The chemiluminescent emission of lifted flames was also low, however, the OH* emission of straight flames was clearly observable and followed the trends of NO emission. The MTC mode may lead to significantly decreased pollutant emission of steady-operating devices like boilers, furnaces, and both aviation and industrial gas turbines, meaning an outstanding contribution to more environmentally friendly technologies.

Abstract Catalytic fast co-pyrolysis (co-CFP) of bamboo sawdust and waste tire over HZSM-5 and MgO was conducted using a tandem pyrolysis and upgrading system which consists of a bubbling fluidized bed and a fixed bed reactor. HZSM-5 mixed and sequential with MgO modes were studied to explore the additive effect for the promotion of aromatic hydrocarbons. Experimental results indicated that co-CFP of bamboo sawdust with waste tire over pure HZSM-5 increased the yields of pyrolysis oil and char, while the gas yield decreased with the increasing of waste tire percentage in the feedstock blends. The product distribution of pyrolysis oil obtained from co-CFP of bamboo sawdust and waste tire over pure HZSM-5 was dominated by aromatic hydrocarbons, and the relative concentration increased from 26.71 to 71.50% as the waste tire percentage elevated from 0 to 60 wt%. Co-CFP of bamboo sawdust and waste tire using HZSM-5 mixed with MgO mode produced a higher yield of pyrolysis oil than the sequential mode when HZSM-5/MgO mass ratio was raised from 1:4 to 1:1. However, the sequential mode was proved to be more effective in the promotion of aromatic hydrocarbons than the mixed mode at a higher HZSM-5 proportion. A positive additive effect for alkylbenzenes was found when the sequential mode was used at varying HZSM-5/MgO mass ratios. Regarding the olefins, C10 olefins were main products, and limonene selectivity increased at first and then decreased with the highest selectivity of 38.87% occurring at HZSM-5/MgO of 2:3 in the mixed mode case. The additive effect of HZSM-5 and MgO indicated that both the mixed and sequential modes inhibited the formation of polycyclic aromatic hydrocarbons with the most significant additive effect obtained at HZSM-5/MgO mass ratio of 1:1 using the mixed mode.

The increasing environmental concerns and the significant growth of the waste to energy market calls for innovative and flexible technology that can effectively process and convert municipal solid waste into fuels and power at high efficiencies. To ensure the technical and economic feasibility of new technology, a sound understanding of the characteristics of the integrated energy system is essential. In this work, a comprehensive techno-economic analysis of a waste to power and heat plant based on integrated intermediate pyrolysis and CHP (Pyro-CHP) system was performed. The overall plant CHP efficiency was found to be nearly 60% defined as heat and power output compared to feedstock fuel input. By using an established economic evaluation model, the capital investment of a 5 tonne per hour plant was calculated to be £27.64 million and the Levelised Cost of Electricity was £0.063/kWh. This agrees the range of cost given by the UK government. To maximise project viability, technology developers should endeavour to seek ways to reduce the energy production cost. Particular attention should be given to the factors with the greatest influence on the profitability, such as feedstock cost (or gate fee for waste), maintaining plant availability, improving energy productivity and reducing capital cost.

Abstract Organic Rankine cycle (ORC) is a promising thermal-to-power technology that uses low-temperature heat from various sources including renewable energy and waste heat. A zeotropic fluid ORC offers thermodynamic-performance advantages over pure fluid ORC because of the relatively low irreversibility during the heat transfer process. Nonetheless, zeotropic fluid ORC may incur higher cost than pure fluid ORC because the former has high mass transfer resistance and small temperature difference in the heat exchanger. Limited research has been carried out to enhance thermo-economic performance of zeotropic ORC. In the present study, an ORC that uses zeotropic fluids and undergoes liquid–vapor separation during condensation is proposed. A thermo-economic analysis is developed based on a new optimization model for the proposed ORC. The objective function of the optimization model is the minimization of the specific investment cost. A genetic algorithm is used to solve the optimization model. A case study is then solved to illustrate the advantages of the proposed ORC and validate the proposed thermo-economic optimization method. The results of the thermodynamic analysis show that the condenser area of the proposed ORC is 17.6% lower than that of the conventional ORC under the same working conditions. Thermo-economic optimization results show that the specific investment cost of the proposed ORC is 13.3–18.4% lower than that of the basic ORC. Meanwhile, the second law efficiency of the proposed ORC is 4.2% higher than that of the conventional ORC. A sensitivity analysis is carried out to assess the dependence of the ORC performance on the temperatures of the heat source and the surrounding environment.

A thermoelectric distillation system has recently been demonstrated to have a great potential of improving the efficiency of distillation processes due to the use of waste heat from the hot side of thermoelectric module to assist evaporation while the cold side for condensation. This work investigates the key factors that affect the water production in a thermoelectric distillation system. An experimental investigation was performed to investigate the influence of evaporation temperature, vapour volume, Peltier current and input power on the water production rate. The results of the experiment show that an increase in the sample water temperature from 30 °C to 60 °C led to an increase in total water production by 47%. In addition, an increase in total water production by 58% was obtained by reducing the vapour volume from 600 cm3 to 400 cm3 during a 3-h operation. The maximum water production rate is achieved by appropriate selection and control of the Peltier current to the thermoelectric device based on the operating condition of the distillation system.