An efficient water conditioning system for land‐based abalone aquaculture

Data collected from a single grow‐out tank in an abalone farm in southern New Zealand has highlighted hygiene maintenance problems in the use of semi‐closed water conditioning systems for the aquaculture of New Zealand black foot abalone Haliotis iris. The data shows that semi‐closed systems can have high concentrations of un‐ionized ammonia, which is harmful to the animals. In this paper an alternative open flow‐through system is suggested where energy demand is limited by heat recovery at the grow‐out tank outlet. Using temperature data collected over 1 year, and a previously obtained expression for standing losses, a simple energy model is presented for an open system with heat recovery. To compliment the energy model, a function has been established for abalone production with respect to the concentration of un‐ionized ammonia and water temperature. The energy model and production function are combined to determine the impact of plant design and tank conditions on the economics of the operation for the southern New Zealand climate. It is demonstrated that temperature control is financially preferable to an open system with no temperature control, and estimates of optimum operating conditions are given. Copyright © 2004 John Wiley & Sons, Ltd.     

Using next generation nuclear power reactors for development of a techno‐economic model for hydrogen production

Nuclear and hydrogen are considered to be the most promising alternatives energy sources in terms of meeting future demand and providing a CO?‐free environment, and interest in the development of more cost‐effective hydrogen production plants is increasing—and nuclear‐powered hydrogen generation plants may be a viable alternative. This paper is a report on investigating the application of new generation nuclear power plants to hydrogen production and development of an associated techno‐economic model. In this paper, theoretical and computational assessments of generations II, III+, and IV nuclear power plants for hydrogen generation scenarios have been reported. Technical analyses were conducted on each reactor type—in terms of the design standard, fuel specification, overnight capital cost, and hydrogen generation. In addition, a theoretical model was developed for calculating various hydrogen generation parameters, and it was then extended to include an economic assessment of nuclear power plant‐based hydrogen generation. The Hydrogen Economic Evaluation Program originally developed by the International Atomic Energy Agency was used for calculating various parameters, including hydrogen production and storage costs, as well as equity, operation and maintenance (O&M), and capital costs. The results from each nuclear reactor type were compared against reactor parameters, and the ideal candidate reactor was identified. The simulation results also verified theoretically proven results. The main objective of the research was to conduct a prequalification assessment for a cogeneration plant, by developing a model that could be used for technical and economic analysis of nuclear hydrogen plant options. It was assessed that high‐temperature gas‐cooled reactors (HTGR‐PM and PBR200) represented the most economical and viable plant options for hydrogen production. This research has helped identify the way forward for the development of a commercially viable, nuclear power‐driven, hydrogen generation plant.     

Influence of cooling water temperature on the efficiency of a pressurized‐water reactor nuclear‐power plant

In this study, the influence of the cooling water temperature on the thermal efficiency of a conceptual pressurized‐water reactor nuclear‐power plant is studied through an energy analysis based on the first law of thermodynamics to gain some new insights into the plant performance. The change in the cooling water temperature can be experienced due to the seasonal changes in climatic conditions at plant site. It can also come into the question of design processes for the plant site selection. In the analysis, it is considered that the condenser vacuum varies with the temperature of cooling water extracted from environment into the condenser. The main findings of the paper is that the impact of 1°C increase in temperature of the coolant extracted from environment is predicted to yield a decrease of ～0.45 and ～0.12% in the power output and the thermal efficiency of the pressurized‐water reactor nuclear‐power plant considered, respectively. Copyright © 2005 John Wiley & Sons, Ltd.     

One‐zone simulation model of an oil‐injected screw chiller

This paper presents a one‐zone steady‐state system model of an oil‐injected screw chiller. The model can be used as a design and optimization tool for system performance of multiple‐chiller plant in process industries. All major components of the system are modelled in a modular format including the oil‐injected screw compressor, shell and tube condenser, flooded evaporator and a high side‐float value. The model results are validated with the experimental data from a multiple‐chiller plant at a process industry. The validated results show that the part‐load ratio and the glycol–water temperature at the evaporator inlet significantly affect the system performance as compared to the temperature of cooling water entering the condenser. Copyright © 2004 John Wiley & Sons, Ltd.     

New design of robust PID controller based on meta‐heuristic algorithms for wind energy conversion system

This paper proposes a new robust control method for a wind energy conversion system. The suggested method can damp the deviations in the generator speed because of the penetration of wind speed and load demand fluctuations in the electrical grid. Furthermore, it can overcome the uncertainties of the plant parameters because of load demand fluctuations and the errors of the implementation. The new method has been built based on new simple frequency‐domain conditions and the whale optimization algorithm (WOA). This method is utilized to design a robust proportional‐integral‐derivative (PID) controller based on the WOA in order to enhance the damping characteristics of the wind energy conversion system. Simulation results confirm the superiority and robustness of the proposed technique against the wind speed fluctuations and the plant parameters uncertainties compared with other meta‐heuristic algorithms.     

Mathematical modeling of gasification of high‐ash Indian coals in moving bed gasification system

Simulation of gasification of high‐ash Indian coal in an updraft moving bed gasification system is presented in this paper. A steady one‐dimensional numerical model, which takes into account of drying, devolatilization, combustion and gasification processes, is used to solve the mass and energy balances in the gasification system. The results from the model have been validated against the experimental data available in literature for various types of coals. The predicted product gas composition, its calorific value and the exit temperature are in agreement with the reported results. The validated model is used to study the effect of input parameters such as oxygen content in air stream, steam flow rates and the pressure of the gasification system. Results indicate that the value of oxygen mole fraction around 0.42 in the oxidizer stream can provide optimum performance in oxygen‐based gasification systems. There is a range of steam‐to‐coal ratio that is dependent on the oxygen content in oxidizer stream. For air‐based systems, this value is around 0.4 and for oxygen‐based systems it is 1.5. The gasification performance improves with operating pressure significantly. An operating pressure of around 8 bar and higher, based on the application, can be used for achieving the required performance with high‐ash coals. The model is useful for predicting the performance of high‐ash Indian coals in a moving bed gasification system under different operating parameters. Copyright © 2013 John Wiley & Sons, Ltd.     

Energy and exergy system analysis of thermal improvements of blast‐furnace plants

The blast‐furnace process dominating in the production of steel all over the world is still continuously improved due to its effectiveness (exergy efficiency is about 70%). The thermal improvement consist in an increase of the temperature of the blast and its oxygen enrichment, as well as the injection of cheaper auxiliary fuels. The main aim is to save coke because its consumption is the predominating item of the input energy both in the blast‐furnace plant and in ironworks. Besides coke also other energy carriers undergo changes, like the consumption of blast, production of the chemical energy of blast‐furnace gas, its consumption in Cowper‐stoves and by other consumers, as well as the production of electricity in the recovery turbine. These changes affect the whole energy management of ironworks due to the close connections between energy and technological processes. That means the production of steam, electricity, compressed air, tonnage oxygen, industrial water, feed water undergo changes as well. In order to determine the system changes inside the ironworks a mathematical model of the energy management of the industrial plant was applied. The results of calculations of the supply of energy carriers to ironworks can then be used to determine the cumulative energy and exergy consumption basing on average values of cumulative energy and exergy indices concerning the whole country. Such a model was also used in the system analysis of exergy losses. Copyright © 2005 John Wiley & Sons, Ltd.     

Development of a steady‐state mathematical model for multistage flash (MSF) desalination plant

In this paper, a mathematical model for multistage flash (MSF) desalination plants was developed. The model was based on basic principles of physics and chemistry that describe the stages occurring in the desalination process. The input plant parameters that are known to affect the operation of the MSF desalination plant and its performance was taken into account in the construction of the model. These parameters included make‐up flow, brine recycle flow, seawater flow, seawater temperature, seawater concentration, top brine temperature (TBT), steam temperature and the plant load. For each stage, the developed model was used for predicting the temperatures of the brine, distillate and cooling brine, and the flow rates of brine outlet and distillate production. The developed model was evaluated with the MSF plant vendor simulation results and its actual operating data. The evaluation indicated that model predictions matched well with the vendor simulation results and the plant operating data. The developed model is sufficiently accurate and model predictions can be relied upon. Therefore, it may be recommended for determining optimum set point of a running MSF desalination plant at different loads to maximize the water production or minimize energy consumption. It can also be used to calculate controller set points for different loads of the plant. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of GTHTR300A nuclear power plant design with dry cooling

GTHTR300A is a power plant design based on high‐temperature gas‐cooled reactor. It relies on exclusive dry cooling for production and in emergency, a practice not found in existing and other proposed plants. Besides well‐known environmental benefits, successful use of dry cooling may provide the new found safety advantage because it avoids water‐related event such as tsunami or generation of explosive hydrogen. In the GTHTR300A, the reactor coolant is used to drive a direct‐cycle gas turbine, and further dry systems are provided to meet the three general cooling requirements. The system to reject power generation waste heat couples the reactor and a natural draft air cooling tower by a closed helium circulation loop. Careful design and operational measures are introduced to ensure the viability of economics, which proves difficult in existing plants. Separately, a natural convective air system is used to remove core decay heat in emergency. Detailed simulation shows that the system placed outside the reactor can maintain the temperatures of reactor fuel and structure below design limits even in case of simultaneous loss of coolant and station blackout. Finally, the study shows that the spent fuel may be stored in dry wells and safely cooled by natural convective air. By reliance on economic and safe dry cooling, the design succeeds in making inland construction feasible even without source of cooling water, and the resulting benefit to safety and environment is compelling in light of the 2011 Fukushima accident due to tsunami. Copyright © 2014 John Wiley & Sons, Ltd.     

Experimental study of a bellows‐type reciprocating‐mechanism driven heat loop

The reciprocating‐mechanism driven heat loop (RMDHL) is a novel two‐phase heat transfer device that could find many important applications in energy systems and electronic cooling. However, the previous RMDHL is based on a solenoid driver that may have difficulty in handling a large amount of heat transfer rate over a long distance due to the driver's inability to provide a large displacement volume. To overcome this difficulty, a bellows‐type RMDHL demonstration model has been designed, fabricated, and tested. The results show that the bellows‐type RMDHL has successfully overcome the weakness of the solenoid driver and may be employed for applications involving large heat transfer rates and over a large surface area. Another advantage of the bellows‐type RMDHL is its potential to maintain an exceedingly uniform temperature over a relatively large surface. Additionally, the power consumption of the bellows driver was less than 5 W when the power input to the cold plate was up to 600 W, resulting in the ratio of driver's power input to the heat input to the cold plate being less than 1%, which represents a tenfold improvement over the solenoid‐based RMDHL. All these technical improvements over the previous RMDHL have demonstrated significant progresses towards a refined RMDHL system for energy and electronics cooling applications. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance assessment of a Stirling engine plant for local micro‐cogeneration

In this paper, we evaluate the viability of a 9.5‐kW_e wooden pellet‐fueled Stirling engine‐based micro‐cogeneration plant as a substitute for small‐scale district heating. The district heating systems against which the micro‐cogeneration plant is compared are based either on a pellet‐fueled boiler or a ground‐source heat pump. The micro‐cogeneration and district heating plants are compared in terms of primary energy consumption, CO₂ emissions, and feasibility of the investment. The comparison also considers an optimally operated individual 0.7‐kW_e pellet‐fueled Stirling engine micro‐cogeneration system with exhaust gas heat recovery. The study is conducted in two different climates and contributes to the knowledge base by addressing: (i) hourly changes in the Finnish electricity generation mix; and (ii) uncertainty related to what systems are used as reference and the treatment of displaced grid electricity. Our computational results suggest that when operated at constant power, the 9.5‐kW_e Stirling engine plant results in reduced annual primary energy use compared with any of the alternative systems. The results are not sensitive to climate or the energy efficiency or number of buildings. In comparison with the pellet‐fueled district heating plant, the annual use of primary energy and CO₂ emissions are reduced by a minimum of 25 and 19%, respectively. Owing to a significant displacement of grid electricity, the system's net primary energy consumption appears negative when the total built area served by the plant is less than 1200 m². On the economic side, the maximum investment cost threshold of a CHP‐based district heating system serving 10 houses or more can typically be positive when compared with oil and pellet systems, but negative when compared with a corresponding heat pump system. Copyright © 2010 John Wiley & Sons, Ltd.     

Testing activity‐based costing to large‐scale combined heat and power plant using bioenergy

This paper deals with the energy production and economics of a large‐scale biomass‐based combined heat and power (CHP) plant. An activity‐based costing model was developed for estimating the production costs of the heat and power of the bio‐CHP. A 100 MW plant (58 MW heat, 29 MW electricity) was used as reference. The production process was divided into four stages: fuel handling, fluidized bed boiler, turbine plant, and flue gas cleaning. The boiler accounted for close to 50% of the production costs. The interest rates and the utilization rate of the CHP had a significant effect on the profitability. We found that below 4000–4500 h per year utilization, the electricity production turned unprofitable. However, the heat production remained profitable with high interest rate (10%) and a low utilization rate (4000 h). The profitability also depended on the type of biomass used. We found that, e.g. with moderate interest rates and high utilization rate of the plant, the bio‐CHP plant could afford wood and Reed canary grass as fuel sources. Copyright © 2013 John Wiley & Sons, Ltd.     

Control‐oriented nonlinear modelling of molten carbonate fuel cells

Performance and availability of molten carbonate fuel cells (MCFC) stack are greatly dependent on its operating temperature. Control of the operating temperature within a specified range and reduction of its temperature fluctuation are highly desirable. The models of MCFC stack existing are too complicated to be suitable for design of a controller because of its lack of clear input–output relations. In this paper, according to the demands of control design, a quantitative relations model of control‐oriented MCFC between the temperatures of the stack and flowrates of the input gases is developed, based on conservation laws. It is an affine nonlinear model with multi‐input and multi‐output, the flowrates of fuel and oxidant gases as the manipulated vector and the temperatures of MCFC electrode–electrolyte plates, separator plates as the controlled vector. The modelling and simulation procedures are given in detail. The simulation tests reveal that the model developed is accurate and it is suitable to be used as a model in designing a controller of MCFC stack. Copyright © 2004 John Wiley & Sons, Ltd.     

Dynamic modelling and simulation of a room with hot water baseboard heater

A dynamic model of a room with a hot water baseboard heater is developed. In the modelling methodology used, a typical finned‐tube baseboard heater with its cover was divided into several control volumes. The mass, energy balance and momentum equations were formulated and solved for each control volume. The dynamic model was used to study the effect of important design and operating parameters on the heat output rate of the baseboard heater. Simulation runs showing the dynamic responses of airflow rates, air temperature from the heater, and hot water temperature are presented. Copyright © 2005 John Wiley & Sons, Ltd.     

Multi‐objective design optimization for mini‐channel cooling battery thermal management system in an electric vehicle

Lithium‐ion battery packs have been generally used as the power source for electric vehicles. Heat generated during discharge and limited space in the battery pack may bring safety issues and negative effect on the battery pack. Battery thermal management system is indispensable since it can effectively moderate the temperature rise by using a simple system, thereby improving the safety of battery packs. However, the comprehensive investigation on the optimal design of battery thermal management system with liquid cooling is still rare. This article develops a comprehensive methodology to design an efficient mini‐channel cooling system, which comprises thermodynamics, fluid dynamics, and structural analysis. The developed methodology mainly contains four steps: the design of the mini‐channel cooling system and computational fluid dynamics analysis, the design of experiments and selection of surrogate models, formulation of optimization model, and multi‐objective optimization for selection of the optimum scheme for mini‐channel cooling battery thermal management system. The findings in the study display that the temperature difference decreases from 8.0878 to 7.6267 K by 5.70%, the standard temperature deviation decreases from 2.1346 to 2.1172 K by 0.82%, and the pressure drop decreases from 302.14 to 167.60 Pa by 44.53%. The developed methodology could be extended for industrial battery pack design process to enhance cooling effect thermal performance and decrease power consumption.     

Design,modeling, and analysis of a high performance piezoelectric energy harvester for intelligent tires

Basic parameters affecting vehicle safety and performance such as pressure, temperature, friction coefficient, and contact‐patch dimensions are measured in intelligent tires via sensors that require electric power for operation and wireless communication to be synchronized to the vehicle monitoring and control system. Piezoelectric energy harvesters (PEHs) can extract a fraction of energy that is wasted as a result of deflection during rolling of tires, and this extracted energy can be used to power up sensors embedded in intelligent tires. A new design of PEH inspired from Cymbal PEHs is introduced, and its performance is evaluated in this paper. Cymbal PEHs are proven to be useful in vibration energy harvesting, and in this paper, for the first time, the modified shape of Cymbal energy harvester is used as strain‐based energy harvester for the tire application. The shape of the harvester is adjusted in a way that it can be safely embedded on the inner surface of tires. In addition to the high performance, ease of manufacturing is another advantage of this new design. A multiphysics model is developed and validated to determine the output voltage, power, and energy of the designed PEH. The modeling results indicated that the maximum output voltage, the maximum electric power, and the accumulated harvested energy are about 3.5 V, 2.8 mW, and 24 mJ/rev, respectively, which are sufficient to power two sensors. In addition, the possibility is shown to supply power to five sensors by increase in piezoelectric material thickness. The effect of rolling tire temperature on the performance of the proposed PEH is also studied.     

Thermal‐hydraulic design features of a micronuclear reactor power source applied for multipurpose

Microheat pipe cooled reactor power source (HRP) designed for space or underwater vehicles meets the future demands, such as safer structure, longer operating time, and fewer mechanical moving parts. In this paper, potassium heat pipe cooled reactor power source system which generates 50 kWe electricity is proposed. The reactor core using uranium nitride fuel is cooled by 37 potassium high‐temperature heat pipes. The shields are designed as tungsten and water, and reactor reactivity is controlled by control drums. The thermoelectric generator (TEG) consists of thermoelectric conversion units and seawater cooler. The thermoelectric conversion units convert thermal energy to electric energy through the high‐performance thermoelectric material. A code applied for designing and analyzing the reactor power system is developed. It consists of multichannel reactor core model, heat pipe model using thermal resistance network, thermoelectric conversion, and thermal conductivity model. Then, the sensitivity analysis is performed on two key parameters including the length of the heat pipe condensation section and the cold junction temperature of the TE cell. Meanwhile, the steady‐state calculations are conducted. Results show that the maximum fuel temperature is 938 K located in the center of reactor core and the outlet temperature of coolant reaches 316 K. Both of them are within the limitation. It is concluded that the preliminary design of HPR design is reasonable and reliable. The designed residual heat removal system has sufficient safety margin to release the decay heat of the reactor. This research provides valuable analysis for the application of micronuclear power source.     

Development and thermodynamic assessment of a novel solar and biomass energy based integrated plant for liquid hydrogen production

In this paper, a combined power plant based on the dish collector and biomass gasifier has been designed to produce liquefied hydrogen and beneficial outputs. The proposed solar and biomass energy based combined power system consists of seven different subplants, such as solar power process, biomass gasification plant, gas turbine cycle, hydrogen generation and liquefaction system, Kalina cycle, organic Rankine cycle, and single-effect absorption plant with ejector. The main useful outputs from the combined plant include power, liquid hydrogen, heating-cooling, and hot water. To evaluate the efficiency of integrated solar energy plant, energetic and exergetic effectiveness of both the whole plant and the sub-plants are performed. For this solar and biomass gasification based combined plant, the generation rates for useful outputs covering the total electricity, cooling, heating and hydrogen, and hot water are obtained as nearly 3.9 MW, 6584 kW, 4206 kW, and 0.087 kg/s in the base design situations. The energy and exergy performances of the whole system are calculated as 51.93% and 47.14%. Also, the functional exergy of the whole system is calculated as 9.18% for the base working parameters. In addition to calculating thermodynamic efficiencies, a parametric plant is conducted to examine the impacts of reference temperature, solar radiation intensity, gasifier temperature, combustion temperature, compression ratio of Brayton cycle, inlet temperature of separator 2, organic Rankine cycle turbine and pump input temperature, and gas turbine input temperature on the combined plant performance.     

Optimizing efficiency and productivity of a dehumidifier batch dryer. Part 1: capacity and airflow

A whole dryer model has been used to investigate the influence of the system design on the efficiency and productivity of a batch‐type dehumidifier dryer. The product is an easy‐to‐dry timber, Pinus radiata. The model, which has been validated at both the dryer and dehumidifier levels, includes sub‐models for the whole dryer energy balance, control of preheating, temperature and relative humidity, and the airflow system. The dynamic response of the system is illustrated and the influence of the dehumidifier capacity and the kiln airflow rate on the dryer performance is established. The effect of varying the airflow system losses is also determined. On the whole, drying speed and operating income increase with the dehumidifier capacity and the kiln airflow rate. The energy used by the dryer in a complete drying cycle is strongly influenced by the fan power requirements, and the airflow system losses have a significant adverse effect on the operating income. The results demonstrate the importance of balancing the dehumidifier and the airflow system losses in order to obtain an optimum combination of drying speed and energy efficiency. Copyright © 2000 John Wiley & Sons, Ltd.     

Integrated offshore wind farm design: Optimizing micro‐siting and cable layout simultaneously

Electrical layout and turbine placement are key design decisions in offshore wind farm projects. Increased turbine spacing minimizes the energy losses caused by wake interactions between turbines but requires costlier cables with higher rates of failure. Simultaneous micro‐siting and electrical layout optimization are required to realize all possible savings. The problem is complex, because electrical layout optimization is a combinatorial problem and the computational fluid‐dynamics calculations to approximate wake effects are impossible to integrate into classical optimization. This means that state‐of‐the‐art methods do not generally consider simultaneous optimization and resort to approximations instead. We extend an existing model that successfully optimizes cable design to simultaneously consider micro‐siting. We use Jensen's equations to approximate the wake effect in an efficient manner, calibrating it with years of mast data. The wake effects are precalculated and introduced into the optimization problem. We solve simultaneously for turbine spacing and cable layout, exploiting the tradeoffs between these wind farm features. We use the Barrow Offshore Wind Farm as a case study to demonstrate realizable savings up to 6 MEUR over the lifetime of the plant, although it is possible that unforeseen design constraints have implications for whether the savings seen in our model are fully realizable in the real world. In addition, the model provides insights on the effects of turbine spacing that can be used to simplify the design process or to support negotiations for surface concession at the earlier stages of a project.