Usable Heat Research Articles

Efficient natural gas combustion and NOx reduction: A novel application of simultaneous over-fire air (OFA) and flue gas recirculation (FGR) in a 250 MW opposed firing steam power plant boiler

OFAGR, as a new controllable technology, combines over-fire air (OFA) and flue gas recirculation (FGR) systems for modifying combustion characteristics and enhancing boiler efficiency. It also reduces NOx generation considerably. The effects of OFA and FGR on the combustion are reported for coal-fired boilers, however, no reference was found for the application of OFAGR, especially in boilers with natural gas fuel so far. Furthermore, the method of adjusting the ratio of OFA and FGR in OFAGR nozzles to achieve the required combustion modification is not investigated and this fact should be even covered for different types of boilers. For analysis of complicated combustive mixed fuel (natural gas) and air in furnace, computational fluid dynamics (CFD) simulated the flow by the use of Eddy-Dissipation Concept (EDC) and developing reactions by Jones-Lindstedt mechanism. Simulation results are validated by the measured boiler operation data for a 250 MW steam power plant boiler. The staged combustion in each burner is modeled by considering three inlet air flows (primary, secondary, and tertiary) with swirl. The effects of different ratios of OFA and FGR streams on characteristics of combustion and NOx production are investigated. The combustion efficiency, temperature profile, distribution of species, and the transferred heat flux to water-walls are computed, and analyzed. Results showed injecting only OFA from OFAGR nozzles, reduced NOx generation up to 55.4 % but lowered the furnace efficiency from 95.3 % to 93.1 %. When the OFAGR stream contained 25 % FGR and 75 % OFA (case study 2), an ideal state existed for increasing the combustion efficiency from 95.3 % to 96.0 % and NOx reduction by 58 %. Increasing the share of FGR in the OFAGR stream by more than 25 % improved the NOx reduction but reduced the combustion efficiency from 95.3 % due to the drop in the usable absorption heat of the boiler. Calculations showed that the OFAGR injection stream containing 64.1 % OFA and 35.9 % FGR reduced NOx formation from 274 to 112 ppm without losing furnace efficiency.

Numerical Analysis of Low-Enthalpy Deep Geothermal Energy Extraction Using a Novel Gravity Heat Pipe Design

Geothermal energy, derived from the Earth’s internal heat, can be harnessed due to the geothermal gradient between the Earth’s interior and its surface. This heat, sustained by radiogenic decay, varies across regions, and is highest near volcanic areas. In 2020, 108 countries utilised geothermal energy, with an installed capacity of 15,950 MWe for electricity and 107,727 MWt for direct use in 2019. Low-enthalpy sources require binary systems for power production. Open-loop systems face issues like scaling, difficult water treatment, and potential seismicity, while closed-loop systems, using abandoned petroleum or gas wells, reduce costs and environmental impacts greatly. The novel geothermal gravity heat pipe (GGHP) design eliminates parasitic power consumption by using hydrostatic pressure for fluid circulation. Implemented in an abandoned well in north-east (NE) Slovenia, the GGHP uses a numerical finite difference method to model heat flow. The system vaporises the working fluid in the borehole, condenses it at the surface, and uses gravitational flow for circulation, maintaining efficient heat extraction. The model predicts that continuous maximum capacity extraction depletes usable heat rapidly. Future work will explore sustainable heat extraction and potential discontinuous operation for improved efficiency.

Waste-to-Energy Processes as a Municipality-Level Waste Management Strategy: A Case Study of Kočevje, Slovenia

The escalating challenge of waste management demands innovative strategies to mitigate environmental impacts and harness valuable resources. This study investigates waste-to-energy (WtE) technologies for municipal waste management in Kočevje, Slovenia. An analysis of available waste streams reveals substantial energy potential from mixed municipal waste, biodegradable waste, and livestock manure. Various WtE technologies, including incineration, pyrolysis, gasification, and anaerobic digestion, are compared. The results show that processing mixed municipal waste using thermochemical processes could annually yield up to 0.98 GWh of electricity, and, separately, 3.22 GWh of useable waste heat for district heating or industrial applications. Furthermore, by treating 90% of the biodegradable waste, up to 1.31 GWh of electricity and 1.76 GWh of usable waste heat could be generated annually from biodegradable municipal waste and livestock manure using anaerobic digestion and biogas combustion in a combined heat and power facility. Gasification coupled with a gas-turbine-based combined heat and power cycle is suggested as optimal. Integration of WtE technologies could yield 2.29 GWh of electricity and 3.55 GWh of useable waste heat annually, representing an annual exergy yield of 2.98 GWh. Within the Kočevje municipality, this amount of energy could cover 23.6% of the annual household electricity needs and cover the annual space and water heating requirements of 10.0% of households with district heating. Additionally, CO2-eq. emissions could be reduced by up to 20%, while further offsetting emissions associated with electricity and district heat generation by 1907 tons annually. These findings highlight the potential of WtE technologies to enhance municipal self-sustainability and reduce landfill waste.

Radiative Impact on Jeffery Trihybrid Convective Nanoflow over an Extensible Riga Plate: Multiple Linear Regression Analysis

Solar thermal systems utilize solar energy to generate heat, and the incorporation of nanoparticles such as Al2O3-Cu-Ni with a water base can elevate their efficiency. These nanofluids, composed of aluminum oxide, copper, and nickel nanoparticles dispersed in water, enhance heat absorption and transfer within the system. This improvement contributes to heightened overall performance and effectiveness of solar thermal systems. Cupronickel alloy helps in the process of desalination. Hence, this study examines the heat exchange properties in the context of a boundary layer flow of a trihybrid over a variable-thickness Riga plate stretched and heated by convective heat with non-Newtonian fluid (Jeffery) in the presence of thermal radiation. The governing equations of the boundary layer are transformed into a system of ordinary differential equations through appropriate similarity transformations, and those equations are resolved utilizing a boundary value problem program. The engineering parameters are analyzed through the application of multiple linear regression. The key finding of the investigation is that the Prandtl number, and thickness index number all have a positive impact on the Nusselt number. The presence of radiation and a uniform heat source improves the Nusselt number, physically this energy transfer improvement assists in higher solar collector efficacy; and converts that energy to usable heat. The rationale behind selecting trihybrid nanoparticles Al2O3, Cu, and Ni lies in the balance and inertness of Al2O3, with metals Cu, and Ni, both possessing more thermal conductivity.

Recent Advancement in Solar‐Driven Interfacial Steam Generation for Desalination: A State‐of‐the‐Art Review

Solar energy is one of the most efficient origins of energy for a wide range of environmentally beneficial purposes. Water desalination by steam generation with the help of solar energy is not only an economical and straightforward approach, but it also utilizes free energy sources to solve the problem of increasing freshwater scarcity. Solar water evaporation is an essential component of the low‐energy method for generating fresh water, which is required for economic development and human health. Freshwater productivity determines how effectively the system captures incoming solar energy and transforms it into usable heat. Effective water distillation has recently gained a lot of attention. The photothermal conversion process is built on the performance of the evaporator. This review thoroughly examines the most recent developments in photothermal materials, structure design, and engineering strategies, including design principles for highly efficient photothermal conversion, thermal management, water transport phenomena, salt rejection behavior, and improved evaporation rate. The prospective applications of this technique in saline water desalination, waste water purification, and energy generation are highlighted. Furthermore, the most recent scientific advancements are utilized to demonstrate the potential, prospects, and challenges of solar‐driven evaporation in energy conversion.

Performance prediction of single-pass and multi-pass low-cost solar air heater

This study introduces a mathematical model and experimental evaluation of solar air heating utilising an absorber surface constructed from low-cost upcycled materials. The research presents a solar air heater prototype, suitable for applications such as space heating and agricultural drying. The solar heating system was modelled using upcycled beverage aluminium cans, considering both single and multi-pass flow configurations. Performance in terms of useful heat was determined through both mathematical model simulations and experimental methods. The multi-pass system demonstrated superior performance, delivering increased usable heat at elevated temperatures compared to the single-pass system. A comparative analysis and validation were conducted between numerical investigations with natural and forced convection on the five-pass solar air heater and experimental test outcomes. This research highlights the potential of utilising waste materials to develop cost-effective, solar heating solutions, contributing to energy management and waste reduction strategies. The findings can be explored for future explorations into sustainable and renewable energy solutions, particularly beneficial in regions with constrained economic resources.

4E evaluations of salt hydrate-based solar thermochemical heat transformer system used for domestic hot water production

A critical step toward the widespread use of renewables is the development of effective energy storage technology. An impressive solution for energy storage and heat upgrade is the salt hydrate-based solar thermochemical heat transformer (THT). The article aims at the temperature lift effects of pressurization-assisted THT systems employing different salts to fulfill the heat requirements of domestic hot water (DHW) generation. To grasp the sustainability of the GJ-level THT systems, energy, exergy, economic, and environmental (4E) assessments are performed under various working conditions. Results manifest that the majority of THT systems enable discharging temperatures (Tdis) to surpass 65 °C, matching regular DHW production. Tdis can be further boosted by the two-stage pressurization whereas at the expense of lowering thermodynamic properties. The SrBr2-based system almost exhibits the best 4E performances with a Tdis of 74.3 °C, although its levelized energy cost (LEC) of 0.1162 $/kWh is slightly higher than that of the LiOH-based system (0.1147 $/kWh). Both systems yield great useable heat, up to 11,667 MJ and 11,140 MJ, respectively, with maximum exergy efficiency of 89.16 % and 63.41 %. Albeit capable of generating higher temperature DHW (≥90 °C), the useable heat and thermodynamic performances of the FeCl2 and CaCl2 based systems are unsatisfactory. By contrast, the K2CO3 and LiOH based systems render higher temperature DHW while ensuring acceptable thermodynamic properties and useable heat. Targeting the regular and higher temperature DHW productions, the lowest CO2 emissions are separately achieved by the SrBr2 and LiCl based systems, i.e., 15 kg/MWh and 56.2 kg/MWh; and the former shows the slowest growth rate in carbon emission with increased Tdis. Augmenting solar irradiation and duration contributes to reducing LEC, and the ideal operating conditions in thermo-economic performance may differ from system to system.

Investigation of Hardfacing on Ultra-High Strength Steel Base Material

The application of high-strength steels is increasing rapidly nowadays, and steels with more than 1000 MPa yield strength are usually used in welded structures. The welding of these materials has many difficulties, so very important the precise technology planning, and disciplined work during welding. The weldability of these materials is commonly investigated field in case of joining. The application of ultra-high strength steels expands rapidly, and in the last years, it started to use them as a base material for hardfacing. Besides the wearing, there is a claim about higher strength of base materials in case of relatively extremely loaded machines. Because this ultra-high strength steel appears as a base material for hardfacing and it brings new challenges for welding technologists. In case of joining, the welding technology is complicated, usually need preheating before welding, is important to calculate and to use the right t8/5 cooling time, and basically necessary to decrease the heat input as much as possible. The bad effect of welding heat input can be compensated by the filler material too in some cases. In contrast in case of hardfacing the base material itself usually has a big thickness, and no joint preparation, additionally important to reach deep fusion on the surface. It basically determines the heat input which has a different heat cycle as in case of joining. Therefore, the heat affected zone (HAZ) differs from the HAZ in case of joining application. In this investigation, four different hardfacing were made with four different technological parameters by robotic gas metal arc welding on S1100QL steel. During the welding parameter determination, we try to find a series of heat inputs from the lowest to the practically usable highest heat input. For the experiments, two filler materials used, one for the buffer zone, and for the hardfacing itself. Microstructural evaluation and hardness tests were made on the specimens which can show the differences between the heat affected zones.

Recovery of fluoride from spent cathode carbon block by combustion combined with water leaching process

Spent cathode carbon blocks (SCCBs) is a kind of hazardous waste that can be harmful to the environment. In this study, a process of high-temperature combustion combined with water leaching was explored to dissociate toxic substances from SCCB and recover valuable components. Combustible components in SCCB can be converted into useable heat energy. The combustion parameters and water leaching process were optimized, and the transformation trend of important components was explained. According to the experimental findings, under optimal conditions, the combustion weight loss rate of SCCB reaches 81.5%, and the defluorination rate reached 88.2%. The toxic leaching concentration of fluoride from the treated residue was reduced to 49 mg L−1, in line with the safe discharge standard. The characterization results showed that the final recovered product was highly similar to its analytical reagent counterpart. This treatment process has the environmental benefits of secondary resource recycling and can effectively reduce the negative impact of SCCB on the environment.

Construction of a model for an enclosing structure with a heat-accumulating material with phase transition taking into account the process of solar energy accumulation

This paper proposes a mathematical model and a procedure for calculating the thermal state of the enclosing structure of the building, which includes an energy-active panel that accumulates solar radiation due to the phase transition of the heat-accumulating material. The mathematical model is based on a two-dimensional non-stationary nonlinear equation of thermal conductivity, which describes the process of heat transfer in the bearing layer of the enclosing structure and the energy-active panel. The model also includes equations describing radiant heat transfer between opaque and translucent bodies. To correctly describe solar insolation, the ASHRAE 2009 model was used in conjunction with the daily change in the position of the Sun in the sky. To solve the system of equations that make up the mathematical model, an iterative procedure has been developed, which involves alternating solution at each time step of the two-dimensional equation of thermal conductivity and a set of algebraic equations of convective and radiant heat transfer. The study’s result established that the amount of accumulated energy in the heat-accumulating material of the phase transition during daylight hours increases significantly, from 15 to 35 %. At night, the surface temperature of the heat-accumulating element in structures using a material with a phase transition is greater than in the case of heat accumulation only in the bearing layer. As a result, it is possible to select from 70 to 120 % more accumulated heat while the presence of high-thermal partitions in a heat-accumulating material with a phase transition contributes to an increase in accumulated heat and usable heat

Entrained flow gasification-based biomass-to-X processes: An energetic and technical evaluation

A large number of process routes is available for the production of sustainable energy carriers from biogenic residues. Benchmarking these routes usually suffers from a lack of comparable performance data. The present work addresses this through a comprehensive model-based comparison of various biomass-to-X routes. Herein, seven routes (methanol, synthetic natural gas, dimethyl ether, Fischer-Tropsch syncrude, ammonia, and hydrogen with and without carbon capture) are modelled in detailed Aspen Plus® simulations. The evaluation itself is based on various key performance indicators, which capture both energetic (i.e. energy yield and usable heat per feedstock) and material-based (i.e. carbon and hydrogen conversion efficiency, and CO2 emissions) properties of the routes. The results show, that no simple correlations can be drawn between energetic and material-based indicators. In summary across all considered properties, the methanol route exhibits the best combined results, in particular with the highest carbon efficiency of 40 %. Fischer-Tropsch is more suitable for integration into existing industrial parks due to the lowest energy yield of 40 % with a lot of by-product formation and the highest amount of useable heat per feedstock of 211.3kWMW-1. Whereas dimethyl ether and synthetic natural gas have potential for integration into heat grids, mainly due to their good conversion and simultaneous large heat dissipation. Ammonia and hydrogen should only be considered in combination with carbon capture. Therefore, the key performance indicators determined herein must be considered together with project- and location-specific requirements and the market outlook for the product.

Using multiple partially-penetrating wells (MPPWs) to improve the performance of high-temperature ATES systems: Well operation, storage conditions and aquifer heterogeneity

The occurrence of free thermal convection negatively affects thermal recovery efficiencies of High-Temperature Aquifer Thermal Energy Storage (HT-ATES) systems. In this study the potential of applying a Multiple Partially Penetrating Well (MPPW) configuration to counteract the impact for seasonal HT-ATES is tested through numerical modeling with SEAWATv4. For scenarios where the thermal front is close to the HT-ATES well-screen and free thermal convection has considerable effect on the thermal recovery efficiency, the use of a MPPW configuration has great potential. Storage at a moderate temperature contrast (ΔT = 40 °C) between the hot injection volume and cold ambient groundwater in a high-permeability aquifer resulted in significant improvement of the thermal recovery efficiency with a MPPW configuration targeting injection in lower parts of the aquifer and recovery in the upper parts. For conventional, fully screened HT-ATES a thermal recovery efficiency of 0.43 is obtained while this is 0.59 with the MPPW scheme in the first recovery cycle. This recovery efficiency of 0.59 is only 0.11 less than a theoretical case with no buoyancy effects. For seasonal HT-ATES cases that face severe free thermal convection, rapid accumulation of heat in the upper part of the aquifer is observed and the MPPW configuration is less effective due to the long period between injection and recovery. Especially for HT-ATES cases that require a cut-off temperature, thermal recovery can be significantly improved and prolonged. For storage temperatures of 60 and 80 °C in a high-permeability aquifer, approximately 4 times more abstracted usable heat is obtained with the MPPW setup while considering a cut-off temperature of 40 °C. Moreover, the present study shows that the use of MPPW configurations in heterogeneous aquifers should be carefully planned. Improper application of MPPW is particularly vulnerable for simplification of the aquifer characteristics, and therefore proper site heterogeneity investigation and operational monitoring are required to benefit from optimal MPPW operation during HT-ATES.

Numerical investigation of fluid flow and heat characteristics of a roughened solar air heater with novel V-shaped ribs

Solar air heaters convert clean solar energy into useable heat and thus have a wide range of applications. Computational fluid dynamics (CFD) can aid in the design and development of solar air heaters with optimized thermal efficiency. A detailed numerical study was conducted to investigate the fluid flow and heat transfer characteristics of a roughened solar air heater with novel V-shaped ribs having staggered elements. Three-dimensional steady-state numerical simulations were performed using the k− ε Re-Normalisation Group (RNG) turbulence model, and results were found to be in excellent agreement with experimental data. The effect of rib spacing was studied through varying the rib pitch to rib height ratio P: e = 6–14, for Reynolds numbers (Re) in the range of 4000–14 000. A significant enhancement in the rib-roughened solar air heater's thermal performance was observed. It was also established that an increment in P: e from 6 to 10 increases the Nusselt number (Nu) for all Re values investigated. About 72.6% Nu enhancement was predicted for P: e = 10 at Re = 12 000. It was further observed that an increment in P: e from 10 to 14 decreases the Nu for all values of Re considered.

Performance analysis of a large TES system connected to a district heating network in Northern Italy

The addition of storage capacity to district heating systems increases flexibility and expands the range of usable heat sources. Despite their apparently simple nature, thermal energy storage (TES) tanks display a wide range of performances due to different construction and operation choices, as proven by numerous literature studies. However, most of the investigations focus on domestic-size tanks of few cubic metres or, on the other hand, very large seasonal storages of hundreds of thousands of cubic metres. In this work, the performances of a 5000 m3 TES recently introduced in a district heating network in Brescia, Italy, are experimentally analysed using temperature and flow rate measurements acquired over two months in the heating season. First-law efficiencies, exergy, and stratification parameters are calculated and discussed. Energy and exergy efficiencies computed for all examined cycles are above 90%, in line with literature values for smaller and larger TESs. The thermocline profile is generally stable through the cycle unless anomalous events occur, and its average thickness is below 4% of the water height. The combined analysis of single-point indicators, thermocline profiles, and qualitative temperature heatmaps shows that short partial charge/discharge events followed by long stand-by periods negatively affect performances. Stratification efficiency and stratification number give further time-dependent information on the vertical distribution of temperatures in the TES. Heat losses towards the outside are also estimated and discussed in the light of integrative measurements performed on other TESs with similar characteristics, showing that particular care must be paid to the top, where dissipation could be increased by evaporation phenomena if the water surface is not protected.

Thermodynamic analysis of subcritical High-Temperature heat pump using low GWP Refrigerants: A theoretical evaluation

An Industrial heat pump recovers low-grade waste heat from the industrial processes and upgrades it into usable heat, obviating the need for conventional boilers. The subcritical technique of high-temperature heat pumps (HTHP) has proven to be an environmentally friendly solution for a wide variety of industrial processes requiring temperatures between 100 °C and 150 °C. The purpose of this paper is to determine the feasibility of a high-temperature heat pump operating over a wide temperature range and utilising an eco-friendly working fluid other than the relatively high GWP R245fa. Environmental and thermodynamic characteristics of R1233zd(E), R1336mzz(Z) and R601 are evaluated and compared to R245fa. A steady-state thermodynamic model of a single-stage HTHP with an additional internal heat exchanger was developed to determine system operational constraints and assess the cycle’s energetic and exergetic performance. The minimum degree of superheating for dry refrigerants is mapped to assess the specific performance at different temperature lifts. The evaporator and condenser heat transfer coefficients are computed and theoretically analysed. The energetic findings confirmed that using R1233zd(E), R1336mzz(Z), and R601 as working fluids enhanced the coefficient of performance (COP) by up to 8.32 %, 11.68 %, and 19.61 %, respectively, in comparison to R245fa. According to the exergetic results, the compressor followed by the expansion process has the greatest thermal losses and therefore has the most potential area for future improvement. Furthermore, R1336mzz(Z) and R601 require larger compressor sizes when compared to R1233zd(E) due to their lower volumetric heat capacity value. Based on the environmental analysis of direct and indirect emissions, utilising low GWP refrigerant results in a significant reduction in the total environmental impact value when compared to using R245fa.

Review of Thermochemical Technologies for Water and Energy Integration Systems: Energy Storage and Recovery

Thermochemical technologies (TCT) enable the promotion of the sustainability and the operation of energy systems, as well as in industrial sites. The thermochemical operations can be applied for energy storage and energy recovery (alternative fuel production from water/wastewater, in particular green hydrogen). TCTs are proven to have a higher energy density and long-term storage compared to standard thermal storage technologies (sensible and latent). Nonetheless, these require further research on their development for the increasing of the technology readiness level (TRL). Since TCTs operate with the same input/outputs streams as other thermal storages (for instance, wastewater and waste heat streams), these may be conceptually analyzed in terms of the integration in Water and Energy Integration System (WEIS). This work is set to review the techno-economic and environmental aspects related to thermochemical energy storage (sorption and reaction-based) and wastewater-to-energy (particular focus on thermochemical water splitting technology), aiming also to assess their potential into WEIS. The exploited technologies are, in general, proved to be suitable to be installed within the conceptualization of WEIS. In the case of TCES technologies, these are proven to be significantly more potential analogues to standard TES technologies on the scope of the conceptualization of WEIS. In the case of energy recovery technologies, although a conceptualization of a pathway to produce usable heat with an input of wastewater, further study has to be performed to fully understand the use of additional fuel in combustion-based processes.

Tilt Angle Optimization and Investigation of the Behavior of a Flat Plate Solar Collector Using MATLAB for Kurdistan Climate Conditions-Iraq

The goal of this study is to investigate the heat transfer as well as optimizing the tilt angle of an active flat plate solar collector. In addition, MATLAB software is used for study the flat plate solar performance of the collector. The entire test rig, with a complete control system, has been set up to collect practical data in September and October 2021. The results showed that the collector efficiency rises with the usable heat rate, peaking at 77% in the autumn (14 October) at the optimal heat rate of 975 W and an outlet water temperature of 64℃. However, the system efficiency for the sunny environment is 53% with an outlet temperature of 36℃ in winter (6 Jan). According to this investigation, the monthly average value and yearly value of optimum tilt angle were found to be 30° to 40° and 30°, respectively, for Erbil climate conditions. Also, this study reveals that the average heat loss coefficient between theoretical models and experimental work was 4.352 W/m2.℃. Furthermore, the temperature difference, corresponding to the same amount of heat loss coefficient, was 14.4℃ for the practical model but 15.25℃ for the theoretical part. This study proposes that using the entire experimental data from a Flat Plate Solar Collector instead of using average values and comparing it to the mathematical equations implemented in the MATLAB software, the thermal efficiency of the system was increased by 5%.

Energy Cell Simulation for Sector Coupling with Power-to-Methane: A Case Study in Lower Bavaria

In this study, the possibility of sector coupling with biological Power-to-Methane to support and stabilize the energy transition of the three major sectors of electricity, heat, and gas was addressed. For this purpose, the energy cell simulation methodology and the Calliope tool were utilized for energy system optimization. This combination provides detailed insights into the existing dependencies of consumers and fossil and renewable energy suppliers on a local scale. In this context, Power-to-Methane represents an efficient technology for quickly and effectively exploiting unused electricity potential for various sectors and consumers. It was found that, even in regions with low wind levels, this surplus electricity potential already exists and depends on various influencing factors in very different ways. The solar influence on these potentials was considered in connection with gas-fired cogeneration plants for district heating. It was found that the current heat demand for district heating produces a large amount of electricity and can generate surplus electricity in the winter. However, in the summer, large amounts of usable waste heat are dissipated into the environment, owing to the low consumption of district heat. This problem in the heat sector could be reduced by the expansion of photovoltaics, but this would require further expansion of storage or conversion systems in the electricity sector. This demonstrates that the consideration of several sectors is necessary to reflect the complexity of the sector coupling with Power-to-Methane properly.

Дулаалгын тунгалаг системүүд

Abstract: In a southerly oriented facade, a Transparent Thermal Insulation (TI) converts incoming solar radiation into usable heat which can be transported to the interior of the building. Transparent insulations are generally installed in front of massive building walls wich serve as energy storage. Different variations of installations have been simulated with a computer program. Real weather data from the Test Reference Year for Ulaanbaatar, Mongolia have been taken into account, a heat gain of as high as 175,8 kWh/m2 seems attainable in wintertime.

Technical and economic assessment of ORC and cogeneration including a combined variant – A case study for the Polish automotive fastener industry company

The global increase in electricity prices seen in recent years contributes to the development of combined heat and power (CHP), which is easily becoming an available technology to improve energy efficiency in manufacturing plants, with a simple payback time of the investment becoming more beneficial. The technological process of simultaneous generation of electricity and useable heat, due to lower fuel consumption, gives great economic savings and is environmentally favorable. In Poland, this solution has a significant impact on CO2 reduction, due to the high emission factor of electricity generation resulting from production based mainly on coal. The reduction of CO2 emissions with a simultaneous increase in energy efficiency is reflected in a reduction of production costs, which makes the plant investing in such a solution more competitive in the market. Unfortunately, the companies are not always aware, and able to utilize the full heat potential outcoming as a by-product during electricity generation when generating electricity e.g., in a cogenerator. For this reason, the combination of cogeneration with Organic Rankine Cycle (ORC) technology becomes a promising way to fully utilize waste heat from a cogenerator. In this article, techno-economic analysis of various cogeneration and ORC variants carried out in an industrial plant producing fasteners for the automotive industry is presented and discussed. The analysis also covers the combined variant of cogeneration with ORC. The analysis shows that the continuous increase of electricity prices justifies investment in cogeneration in contrast to the ORC engine, which is characterized by high investment costs and low efficiency, nevertheless, in combination with cogeneration may become more affordable for industrial plants with energy-intensive processes such as heat treatment.