4E comparative analysis of energy transition scenarios for the decarbonization of a chocolate factory utilities in Brazil

Process integration of organic Rankine cycle (ORC) and heat pump for low temperature waste heat recovery

In order to reduce the waste heat emission and environmental impact of industrial processes, Organic Rankine Cycle (ORC) is gradually used for energy recovery. ORC is regarded as the most promising measure for converting low-grade heat into electricity, but commercial applications are still limited due to the high investments and poor economic returns. However, the simultaneous optimization of ORC and Heat Integration can improve system economy. This work proposes a techno-economic optimization model involving the area estimate of heat exchanger based on vertical heat transfer for optimization of ORC and Heat Integration. This model determines the selection of working fluids, the optimal operating parameters of ORC including temperatures, pressures, and flowrate of working fluids. Both of the supercritical and subcritical conditions can be considered in this model. To solve this optimization problem, a bi-level optimization approach is developed, where the outer level uses Genetic Algorithm to identify the promising working fluids and optimize the temperatures and pressures of ORC, and the inner level is an NLP model to find the optimal flowrate of ORC and the vertical matches of streams by minimizing total annual cost. The results represent the necessity of simultaneous optimization of Organic Rankine Cycle and Heat Integration.

Organic Rankine Cycle (ORC) is a promising technology for exploiting the industrial low-grade waste heat. When trying to implement ORCs, proper integration with background waste heat sources is one of the crucial matters that should be considered. Research on ORC integration has been carried out during the last few decades. However, it is observed that the existing methodologies for integrating ORCs into industrial sites are still insufficient. Lots of the research efforts deal with ORC integration problems assuming only one single ORC participates, while the options of applying multi-parallel ORCs are rarely taken into account. Besides, existing research mainly focuses on the direct integration of ORC(s) (i.e. waste heat is transferred directly from heat sources to ORC working fluids), whereas the option of utilizing intermediate heat carriers indirectly is neglected. As such, this study proposes a model-based methodology for the indirect integration of multi-parallel ORCs. The overall model covers both waste heat extraction and ORC power generation. For heat extraction modelling, a modified superstructure based on (Isafiade and Fraser, 2008) [1] is proposed, which simplifies the construction of a heat extraction network (HEN) and reduces computational time. For thermodynamics, the Peng-Robinson Equation of State is adopted. The overall model leads to a mixed-integer nonlinear programming (MINLP) problem and can be solved by a General Algebraic Modelling System, e.g., the GAMS software. Two case studies are performed in this work to validate and illustrate the application of the proposed method, the results of which show that applying multi-parallels ORCs instead of using a single ORC can decrease the overall annualized cost effectively.

A review of heat integration approaches for organic rankine cycle with waste heat in production processes

Process integration of organic Rankine cycle

Internal combustion engines (ICE) are utilized in a number of energy and transportation systems and with the prospect of synthetic green fuels have also secured a place in the future low emission systems. Still, aiming at the effective utilization of the fuel suggests an addition of waste heat recovery systems such as organic Rankine cycle (ORC) to boost electric efficiency. Greater widespread of the ORC integration into the ICE systems is however limited from multiple aspects. Furthermore, when these systems are employed, they are typically applied only for flue gas waste heat utilization, while the large amounts of lower temperature jacket cooling heat remain unutilized, or at the cost of high system complexity. Direct cooling of the ICE jacket by the ORC working fluid has been previously theoretically proposed to tackle some of them. Complexity of the system can be reduced while more waste heat can be effectively transferred from the ICE jacket cooling to the ORC. Here we propose further configuration of ICE waste heat sources integration into a biomass fired ORC unit, creating a multi-fuel system. Such system offers the possibility to increase the electricity demand while reducing biomass consumption. This system has been experimentally explored on a case of a 3 kWe/50 kWth micro-cogeneration ORC and an 8 kWeICE. The experimental data are evaluated in comparison to the theoretically predicted operation. A specific control system has been developed for this system to be easily operated. The results, experience and operation verification from the ICE jacket cooling with the ORC fluid can be also utilized in the construction for waste heat recovery ORC integrated to ICE for higher electrical efficiency. Integration of combined direct jacket and flue gas heat recovery increased the overall electrical efficiency of the system from about 5% for operation of standalone ORC to over 20% for full ICE power.

Energy usually plays a critical role in the development of a country. With the gradual decrease of available traditional fuel reserves and air pollutions problems that being followed by using them, the need to replace alternative renewable and sustainable options to decrease our dependence on fossil fuels has drawn attention. Biomass is a kind of reliable renewable energy that is used to derive combined heat and power systems known as the Organic Rankin Cycle (ORC). This paper presents of exergy analysis of three cycles which have been modeled by EES software for a laundry that needs 32 (kW) power and 2500 (kg/h) 65 (Co) hot water which hot water is our main goal in this study. In RC (gas fuel) and ORC (biomass fuel) power which is produced provides part of electricity needed in the laundry but for Boiler Proving Hot Water (BPHW) the whole electricity needed is bought from the grid. R245fa is a friendly environmentally organic fluid that is used in ORC as a working fluid. The result of this analysis shows for the same conditions the most exergy destruction occurs in the boiler and the least in the pump in three cycles. It also shows the most efficiency of second law respectively is belongs to RC, ORC, BPHW with 0.21%, 0.16%, 9% total efficiency respectively. Moreover, by utilizing EES software and genetic algorithm all of the configurations have been optimized and compared.

Reducing carbon dioxide (CO2) emissions from power plants utilizing fossil fuels is expected to become substantially more important in the near- to medium-term due to increasing costs associated to national and international greenhouse gas regulations, such as the Kyoto protocol and the European Union Emission Trading Scheme. However, since net efficiency penalties caused by capturing CO2 emissions from power plants are significant, measures to reduce or recover efficiency losses are of substantial interest. For a state-of-the-art 400 MW natural gas-fueled combined cycle (NGCC) power plant, post-combustion CO2 removal based on chemical solvents like amines is expected to reduce the net plant efficiency in the order of 9–12 percentage points at 90% overall CO2 capture. A first step that has been proposed earlier to improve the capture efficiency and reduce capture equipment costs for NGCC is exhaust gas recirculation (EGR). An alternative or complementary approach to increase the overall plant efficiency could be the recovery of available low temperature heat from the solvent-based CO2 removal systems and related process equipment. Low temperature heat is available in substantial quantities in flue gas coolers that are required upstream of the CO2 capture unit, and that are used for exhaust gas recirculation, if applied. Typical temperature levels are in the order of 80°C or up to 100 °C on the hot end. Additional low-grade heat sources are the amine condenser which operates at around 100–130 °C and the amine reboiler water cooling that could reach temperatures of up to 130–140°C. The thermal energy of these various sources could be utilized in a variety of low-temperature heat recovery systems. This paper evaluates heat recovery by means of an Organic Rankine Cycle (ORC) that — in contrast to traditional steam Rankine cycles — is able to convert heat into electricity efficiently even at comparably low temperatures. By producing additional electrical power in the heat recovery system, the global performance of the power plant can be further improved. This study indicates a theoretical entitlement of up to additional 1–1.5 percentage points in efficiency that could be gained by integrating ORC technology with a post-combustion capture system for natural gas combined cycles. The analysis is based on fundamental thermodynamic analyses and does not include an engineering- or component-level design and feasibility analysis. Different ORC configurations have been considered for thermal energy recovery at varying temperature levels from the above-mentioned sources. The study focuses on simultaneous low-grade heat recovery in a single ORC loop. Heat recovery options that are discussed include in series, in parallel or cascaded arrangements of heat exchangers. Different organic operating fluids, including carbon dioxide, R245fa, and N-butane were considered for the analysis. The ORC performance was evaluated for the most promising organic working fluid by a parametric study. Optimum cycle operating temperatures and pressures were identified in order to evaluate the most efficient approach for low temperature heat recovery.

This study experimentally investigates the performance of a helical coil integrated chilled water system (HCCWS) used for simultaneous cooling of hot air (HA) and water (HW). The current HCCWS operates with three fluids in which chilled water (CW) flows inside the shell while hot water and air pass through the helical coil and innermost tube. Nusselt number, friction factor, and JF factor are measured as performance of the HCCWS corresponding to variations in inlet temperature, flow rate, and velocity of different fluids respectively. Temperature distribution of different fluids along the length of the HCCWS test section was determined. From results, it is observed that Nusselt number increases considerably as the flow rate of CW increases, reaching a maximum of 150.01 at a flow rate of 200 liter per hour (LPH) and an inlet temperature of 13°C. As the flow rate of chilled water increases, the friction factor drops. The lowest friction factor measured was 0.016 with a flow rate of 200 LPH and an inlet temperature of 13°C. The chilled water inlet temperature and hot water flow rate significantly affect the JF factor of CW, HW, and HA with a contribution of 33.47%, 33.7%, and 32.69%, respectively. The Taguchi-Grey technique was used to optimize the overall JF factor corresponding to input parameters. The optimal HCCWS performance was achieved at 13°C inlet temperature, 100 LPH chilled and hot water flow rates, and 4 m/s hot air velocity, raising the grey relation grade to 1.

In this paper, the integration of Gas Engines with the Rankine cycle and Organic Rankine cycle for use as a combined cooling, heating and power (CCHP) system was investigated. The gas engine model, Organic Rankine Cycle model, Rankine Cycle model and single effect absorption chiller model were developed in Aspen HYSYS V7.3®. The system performance of the combination of the Rankine Cycle and Organic Rankine Cycle was investigated with two different configurations. The series and parallel combination of Rankine and Organic Rankine Cycle integration with the gas engine showed an increase of 7% and 15% respectively both in the overall system efficiency and power generated. The trigeneration system provided a cooling duty of 18.6 kW, a heating duty of 704 kW to a district heating system with 3.9 MW of power generated and an overall trigeneration efficiency of 70%. The system also gave a 9% increase in the power generated when compared to the gas engine without waste heat recovery whilst bottoming with Rankine cycle, Organic Rankine cycle and Absorption refrigeration system.Keywords: Modelling, Trigeneration, Gas Engines, Waste Heat Recovery, Rankine Cycle, Organic Rankine Cycle.

This chapter discusses the application of organic molecules in engineering thermodynamics: being used as working fluid in refrigeration and the organic Rankine cycle. There are, in general, two points of view that may be adopted in the engineering thermodynamics: the macroscopic point of view and the microscopic point of view. Two applications of organic molecules in engineering thermodynamics, refrigeration and the organic Rankine cycle, are not at a molecular scale, but at a human scale.The chapter focuses on the performance of refrigeration system and the organic Rankine cycle that contain many molecules. Main methods of refrigeration can be classified as non-cyclic, cyclic, thermoelectric, and magnetic. Cyclic refrigeration can be classified as: vapor cycle and gas cycle. Vapor cycle refrigeration can further be classified as: vapor-compression refrigeration and vapor-absorption refrigeration. Organic molecules are always used as the working fluids in vapor-compression refrigeration cycle. Besides, organic molecules are also used as the working fluids in ORC that is an important technique for low-grade heat utilization. The development history, numbering system, classification, and requirements of organic refrigerant used in refrigeration system and ORC are also introduced. Keywords: cyclic refrigeration; engineering thermodynamics; non-cyclic refrigeration; organic molecules; organic Rankine cycle; vapor-compression refrigeration cycle; refrigerant

Increasing fuel prices and stringent emission regulations are forcing improvements in the performance and emissions of internal combustion engines (ICEs). There are several ways to enhance engine performance and emissions. Waste heat recovery has emerged as a practical solution in recent times. The Organic Rankine Cycle (ORC) is a promising technology to recover the waste heat from various sources and potentially enhance the overall performance of ICEs. The ORC system converts waste heat energy into useful power either for ICEs, renewable energy (geothermal, solar and biomass), or industrial waste heat energy. The ORC systems range from a few kW to multi-MW plants. After a long evolution, this technology has matured. The economic performance of an ORC is very important for its further development and wider application. Integration of ORC with ICEs is gaining popularity among researchers. However, it isn’t very easy and depends on the physicochemical properties of the working fluid (WF) and the heat source temperature. Several optimization methods could improve its performance and decide the optimum operating conditions for the ORC systems.KeywordsOrganic Rankine cycleWaste heat recoveryWorking fluidEconomy

Integration of Organic Rankine Cycle with Lignite Flue Gas Pre-drying for Waste Heat and Water Recovery from Dryer Exhaust Gas: Thermodynamic and Economic Analysis

Experimental characterization of an ORC (organic Rankine cycle) for power and CHP (combined heat and power) applications from low grade heat sources

A comprehensive review of solar-driven multigeneration systems with hydrogen production