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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] 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] 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: • 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
[en] The feasibility of integrating a commercially available reheat gas turbine with a methane steam reformer is analyzed. A slight modification to the original reheat design is proposed to improve the methane conversion rate in the reforming process and, consequently, the efficiency in recovering waste exhaust heat from the gas turbine. Two solutions are proposed for the heat recovery scheme: a first reformer has a single pressure level while the second has two in order to match the different pressures of the combustors. While the single pressure scheme gives good performance with respect to the stand alone gas turbine, the dual pressure reformer can give a further benefit, as far as an accurate optimization of the steam management is performed
[en] Highlights: • This study was to determine the potential of thermophotovoltaic heat recovery for Turkish industrial sector. • It was performed by using actual data for TIS. • Total technical–potential energy heat recovery in the high-temperature industry was estimated as 447.8 PJ/year. • Electricity can be achieved from 22.40 PJ/year to 67.45 PJ/year according to the TPV efficiencies. • This study will be very beneficial in energy policies of countries in terms of the usage of waste heat energy. - Abstract: Thermophotovoltaics (TPV) are the use of the photovoltaic effect to generate electricity from a high-temperature thermal (infrared) source. This study deals with to provide an overview of heat recovery by TPV from industrial high-temperature processes in Turkish industrial sector. The paper reviews the relevant facts about TPV technology and the high-temperature industry and identifies three principle locations for TPV heat recovery. For each location, one example process is assessed in terms of applicability of TPV impact on the existing process and power scale. Knowledge of these factors should contribute to the design of an optimum TPV system. In the TIS, the total technical–potential energy recovery in the high-temperature industry using deployed and demonstrated heat recovery devices for product, flue gas, and wall heat recovery was estimated as 447.8 PJ/year. However, an estimation from 22.40 PJ/year to 67.45 PJ/year can be achieved according to the TPV efficiencies. Also, the paper estimates the range of possible energy savings and the reduction in CO emission using TPV in the high-temperature industry. It is expected that this study will be very beneficial in developing energy policies of countries in terms of the usage of waste energy efficiency
[en] Highlights: • We analyzed the feasibility of an “on-board” ORC recovery system to power auxiliaries. • Performance of the ORC cycle has been simulated with CAMEL-Pro™. • Several relevant ORC components have been designed. • Approximate characteristics dimensions of HRSG and evaporator have been calculated and a preliminary layout provided. • The evaluation of a possible assembling of the system has been developed. - Abstract: This paper analyses the feasibility of an “on-board” innovative and patented ORC recovery system. The vehicle thermal source can be either a typical diesel engine (1400 cc) or a small gas turbine set (15–30 kW). The sensible heat recovered from the exhaust gases feeds the energy recovery system that can produce sufficient extra power to sustain the conditioning system and other auxiliaries. The concept is suitable for all types of thermally propelled vehicles, but it is studied here for automotive applications. The characteristics of the organic cycle-based recovery system are discussed, and a preliminary design of the main components, such as the heat recovery exchanger, the evaporator and the pre-heater is presented. The main challenge are the imposed size and weight limitations that require a particular design for this compact recovery system. A possible system layout is analyzed and the requirements for a prototypal application are investigated
[en] Highlights: • An indirect contact heat recovery process from molten salt is modelled. • Predicted results for axial growth of the solid layer are presented. • Variations of the coolant and wall temperatures are presented and discussed. • The effects of the inner tube diameter and the coolant mass flow rate are investigated. - Abstract: An analysis is presented for the heat transfer from molten salt in the copper–chlorine thermochemical cycle for hydrogen production. For this cycle to become economical relative to other existing or developing technologies, effective heat recovery is very important. Heat recovery processes are investigated from molten CuCl (a product of the copper oxychloride decomposition process in the Cu–Cl cycle). Recovering heat from molten CuCl at 500 °C is challenging due to its phase change from liquid to solid. Based on a previous examination of different options for this heat recovery (including atomization with steam generation, casting/extrusion, drum flaker and a rotary spinning atomizer), the casting/extrusion method was deemed advantageous. Hence that process is considered here, with a counter-current air flow as a coolant. Predicted results for axial growth of the solid layer and variations of the coolant and wall temperatures are presented and discussed. The effects of the inner tube diameter and air mass flow rate are also investigated
[en] Highlights: ► The characteristic of the exhaust waste heat for a light duty diesel engine is analyzed. ► A mathematical model is established for a finned-tube evaporator used in an ORC. ► The heat transfer performance of the finned-tube evaporator is evaluated throughout the engine’s operating region. - Abstract: The organic Rankine cycle (ORC) can be used to recover waste heat from an internal combustion engine. In such a system, the evaporator design is critical. Determining the amount of heat that can be transferred in a designed evaporator is extremely important for a successful ORC system. In this paper, the performance of a finned-tube evaporator used to recover exhaust waste heat from a diesel engine is presented. First, the exhaust heat of the chosen diesel engine is evaluated based on the measured data. Subsequently, a mathematical model of the evaporator is created based on the detailed geometry and the specific ORC working conditions. Then, the heat transfer of the evaporator is estimated as the diesel engine runs through all of its operating regions defined by the engine speed and the engine load. The results show that the exhaust temperature at the evaporator outlet increases with engine speed and engine load. Although the convective heat transfer coefficient of the organic working fluid is significantly larger than that of the exhaust gas, the overall heat transfer coefficient is slightly greater than that of the exhaust gas. Furthermore, the heat transfer rate is the greatest in the preheated zone and least in the superheated zone. Consequently, the heat transfer area for the preheated zone is nearly half of the total area. In addition, the area of the superheated zone is slightly greater than that of the two-phase zone. It is concluded that the heat transfer area for a finned tube evaporator should be selected carefully based on the engine’s most typical operating region.