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[en] A thermoeconomic feasibility analysis is presented yielding a simple algebraic optimization formula for estimating the optimum length of a finned pipe that is used for waste heat recovery. A simple economic optimization method is used in the present study by combining it with an integrated overall heat balance method based on fin effectiveness for calculating the maximum savings from a waste heat recovery system
[en] Highlights: • A methodology for energy efficiency of large-scale chemical plants is developed. • A multi-level data extraction for energy requirement definition is introduced. • The practice of total site integration with the combination of levels is shown. • The suitable utilities are integrated and optimized for different proposals. • A Pareto analysis is performed to find the optimum combination of levels. - Abstract: This study presents a methodology based on process integration techniques to improve the energy efficiency of a large-scale chemical plant. The key to the approach is to represent the energy requirements with different heat transfer interfaces. Considering difficulties of data extraction for a large-scale plant, a multi-level data extraction scheme is introduced based on different heat transfer interfaces and includes five levels of growing complexity: black-box, grey-box, white-box, simple-model and detailed-model analysis. A combination of these levels instead of a single definition for the energy requirement has been applied on an industrial case study. Different steps of the approach are explained in detail and their potential are highlighted. The Single Process Integration (SPI) and Total Site Integration (TSI) has been performed and revealed that a higher potential of heat recovery could be driven through the TSI. The optimized site utility integration together with heat recovery improvement scenarios have considerably increased the energy saving potential in our case study. A multi-objective optimization has also been performed to find the optimum combination of units with different energy requirement levels. In conclusion, results from our case study have indicated that using a combination of different energy requirement levels will reduce the required modification of the actual site configuration
[en] In this research, a vortex generator heat exchanger is used to recover exergy from the exhaust of an OM314 diesel engine. Twenty vortex generators with 30° angle of attack are used to increase the heat recovery as well as the low back pressure in the exhaust. The experiments are prepared for five engine loads (0, 20, 40, 60 and 80% of full load), two exhaust gases amount (50 and 100%) and four water mass flow rates (50, 40, 30 and 20 g/s). After a thermodynamical analysis on the obtained data, an optimization study based on Central Composite Design (CCD) is performed due to complex effect of engine loads and water mass flow rates on exergy recovery and irreversibility to reach the best operating condition. - Highlights: • A vortex generator heat exchanger is used for diesel exhaust heat recovery. • A thermodynamic analysis is performed for experimental data. • Exergy recovery, irreversibility are calculated in different exhaust gases amount. • Optimization study is performed using response surface method
[en] Highlights: • Methodology development for Total Site heat recovery with of intermediate utility. • Selection of temperature for intermediate utilities of Total Site. • Capital cost reduction for heat exchangers network design on Total Site level. • Recommendation for selection of heat exchangers design of Total Site. - Abstract: In this paper a further development of methodology for decreasing the capital cost for Total Site heat recovery by use of different utility levels is proposed. The capital cost of heat recovery system is estimated for certain temperature level of intermediate utility applying Total Site Profiles. Heat transfer area is reduced by selection of appropriate temperature of intermediate utility. Minimum of heat transfer area depends on slopes of Total Site Profiles in each enthalpy interval. This approach allows estimating the minimum of heat transfer area for heat recovery on Total Site level. Case study is performed for fixed film heat transfer coefficients of process streams and intermediate utilities. It indicates that the total heat transfer area of heat recovery can be different up to 49.15% for different utility temperatures
[en] A new local ventilation device is actually developed in such a way to procure ventilation 'on demand' in each room, with a maximal effectiveness. It consists in a wall or window frame mounted plane-parallel box, containing two (injection and extraction) fans, an electronic control, and a heat recovery exchanger. The present paper describes the experimental investigations carried out on some single components and on the entire unit in order to characterize the aeraulic and thermal performance of the device.
[en] Highlights: • A new practical heat integration framework was developed for complex and diverse production lines. • Heat recovery was maximised by direct and indirect heat integration at zonal and factory levels. • A novel approach to stream data extraction was proposed to account for both stream capacity and availability. • A case study was carried out on a multi-product confectionery factory. - Abstract: Heat integration is a key measure to improving energy efficiency and maximising heat recovery. Since the advent of Pinch analysis in the 1980s, direct and indirect integration approaches have developed in separate domains with very few examples where both approaches are utilised together to maximise heat recovery. This paper presents a novel decision-making framework for heat integration in complex and diverse production lines, with the aim to provide the user with a step-by-step guide to evaluate all heat recovery opportunities through a combination of direct and indirect heat integration. This framework involves analysis at both the zonal level and the factory level. The proposed framework was applied to a case study based on a confectionery factory in the UK that manufactured multiple products across a diverse range of food technologies. It demonstrates that the framework can effectively identify the significant streams to be considered in the heat integration analysis, and address practical factors such as diverse production times, geographical proximity, and potential of compromise to product quality when the direct and indirect heat integration opportunities are proposed and assessed both within and between production zones. This practical framework has the potential to benefit the wider food industry and beyond
[en] Highlights: • Trigeneration technologies classified and reviewed according to prime movers. • Relevant heat recovery equipment discussed with thermal energy storage. • Trigeneration evaluated based on energy, exergy, economy, environment criteria. • Design, optimization, and decision-making methods classified and presented. • System selection suggested according to user preferences. - Abstract: Electricity, heating, and cooling are the three main components constituting the tripod of energy consumption in residential, commercial, and public buildings all around the world. Their separate generation causes higher fuel consumption, at a time where energy demands and fuel costs are continuously rising. Combined cooling, heating, and power (CCHP) or trigeneration could be a solution for such challenge yielding an efficient, reliable, flexible, competitive, and less pollutant alternative. A variety of trigeneration technologies are available and their proper choice is influenced by the employed energy system conditions and preferences. In this paper, different types of trigeneration systems are classified according to the prime mover, size and energy sequence usage. A leveled selection procedure is subsequently listed in the consecutive sections. The first level contains the applied prime mover technologies which are considered to be the heart of any CCHP system. The second level comprises the heat recovery equipment (heating and cooling) of which suitable selection should be compatible with the used prime mover. The third level includes the thermal energy storage system and heat transfer fluid to be employed. For each section of the paper, a survey of conducted studies with CHP/CCHP implementation is presented. A comprehensive table of evaluation criteria for such systems based on energy, exergy, economy, and environment measures is performed, along with a survey of the methods used in their design, optimization, and decision-making. Moreover, a classification diagram of the main CHP/CCHP system components is summarized. A general selection approach of the appropriate CCHP system according to specific needs is finally suggested. In almost all reviewed works, CCHP systems are found to have positive technical and performance impacts.
[en] Highlights: • A selection map of CTRC toward thermal energy management of engine. • A rapid and effective decision-supporting tool for a general CTRC design. • Comprehensive system performances are considered from three aspects. • The method can be expanded to other recovery system selection. - Abstract: CO_2-based transcritical Rankine cycle (CTRC) can be used for the waste heat recovery due to its safety and environment-friendly characteristics, and also fits for the high temperature of exhaust gas and satisfy the miniaturization demand of recovery systems. It can provide a reasonable pathway toward thermal energy management of engine. This work proposes novel configurations selection maps of four CTRC configurations for waste heat recovery of engines. Except for considering a regenerator added to traditional CTRC (basic CTRC) recovering exhaust waste heat, a preheater driven by engine coolant will be also taken into account in this paper. Thus, the four configurations include the basic CTRC (B-CTRC), the CTRC with a preheater (P-CTRC), the CTRC with a regenerator (R-CTRC) and the CTRC with both of the preheater and the regenerator (PR-CTRC). As different CTRC configurations have advantage of performance indicators under different conditions, and the focused indicators may also be various with applications, this paper focuses on proposing a kind of selection maps, which is used for the selection of the four CTRC configurations in the field of engine waste heat recovery. Comprehensive performance comparison are researched in this paper from three aspects, net power output based on the first law of thermodynamics, exergy efficiency based on the second law of thermodynamics and electricity production cost (EPC) as an indicator of the economic performance. After the comparative analysis, three selection maps separately based on the three performance indicators are proposed to give the selection reference of the CTRC configurations under different design conditions, which refer to turbine inlet pressure and temperature in this paper. It is meaningful for the design and operating of the CTRC configuration used for waste heat recovery of engines. Besides, it can also be a new method that can be expanded to other recovery system selection (e.g. ORCs) in engine field or other fields (e.g. solar, geothermal).
[en] This paper shows a possible way to achieve a thermoeconomic optimization of combined cycle gas turbine (CCGT) power plants. The optimization has been done using a genetic algorithm, which has been tuned applying it to a single pressure CCGT power plant. Once tuned, the optimization algorithm has been used to evaluate more complex plants, with two and three pressure levels in the heat recovery steam generator (HRSG). The variables considered for the optimization were the thermodynamic parameters that establish the configuration of the HRSG. Two different objective functions are proposed: one minimizes the cost of production per unit of output and the other maximizes the annual cash flow. The results obtained with both functions are compared in order to find the better optimization strategy. The results show that it is possible to find an optimum for every design parameter. This optimum depends on the selected optimization strategy
[en] Highlights: • Heat recovery in a heat exchanger network (HEN). • A novel method for on-line determination of the thermal resistance of fouling is presented. • Details are developed for shell and tube heat exchangers. • The method was validated and sensibility analysis was carried out. • Developed approach allows long-term monitoring of changes in the HEN efficiency. - Abstract: A novel method for on-line determination of the thermal resistance of fouling in shell and tube heat exchangers is presented. It can be applied under the condition that the data on pressure, temperature, mass flowrate and thermophysical properties of both heat-exchanging media are continuously available. The calculation algorithm for use in the novel method is robust and ensures reliable determination of the thermal resistance of fouling even if the operating parameters fluctuate. The method was validated using measurement data retrieved from the operation records of a heat exchanger network connected with a crude distillation unit rated 800 t/h. Sensibility analysis of the method was carried out and the calculated values of the thermal resistance of fouling were critically reviewed considering the results of qualitative evaluation of fouling layers in the exchangers inspected during plant overhaul