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This paper was presented during the time the author was president of the Council of Educational Facility Planners, International, (CEFP/I). The presentation begins with a summary of the state of the world's natural gas and petroleum supplies and states that since one-third of all energy consumed in the United States is to heat and cool buildings, schools offer a huge opportunity to conserve vast amounts of energy. The energy policy of CEFP/I is presented and used as the basis for a discussion of the commitment to human as well as finacial considerations in accepting or rejecting an energy conservation matter. The main thrust of the paper is that there is much that can be done today in a building design to dramatically reduce energy use as well as alter how and what energy supply is used. The author discusses 20 specific energy conservation items that can be applied today and describes how his architectural firm uses these considerations in the educational facility planning process. (Author/MLF)

This speech provides concrete ways for school districts to save on energy costs, based on the general concept of flexibility in energy systems. These methods have been successfully implemented in the Salem (Oregon) school district. The first idea is to set up a weekly, rather than annual, bidding system to increase fuel price options. This provides the flexibility to respond to fluctuations in the world energy market, and thereby save considerably on fuel costs while choosing the best quality fuels from competing vendors. Converting boilers to burn either oil or gas will allow school districts to choose whichever fuel is less expensive from week to week. Other methods include selective heating of zones within a building (depending on time of day, usage, and sun exposure), heat recovery systems on air vents, and separate hot water heaters. Because electric companies charge a penalty for peak loads, timers on air circulation equipment enable schools to distribute kilowatt loads more efficiently. Slight decreases in room temperature and lighting also result in significant savings, as does preventive maintenance. Advice is also offered on raising the initial capital needed to institute energy conservation measures, by applying for federal and state grants or matching funds. (TE)

Heat pipes represent a highly effective method of transferring thermal energy from one location to another. Unlike traditional heat pipes, pulsating heat pipes (PHPs) operate without a wick structure. PHPs are compact cooling devices widely employed in various applications, including renewable energy systems, electronic device cooling, and heat recovery systems, among others. A pulsating heat pipe works on principle of capillary tube with a small inner diameter, which in turn uses surface tension mechanism of the working fluid to form pulses. The tube is connected between the evaporator and condenser sections. Due to the presence of two-phase flow phenomena, heat transfer in PHPs is intricate and influenced by several factors, such as number of turns, tube material, thickness, diameter, working fluid, and filling ratio. PHPs offer numerous advantages, including their compact size, simple structure, cost-effectiveness, and efficient heat transfer performance. Consequently, they hold significant potential for various applications, such as refrigeration, roof cooling, waste heat recovery, and micro cooling applications. In this study, a numerical analysis is conducted to assess the thermal performance of pulsating heat pipes using three different models. Water is used as the working fluid for the analysis, and the Volume of Fluid (VOF) model is utilized to simulate the two-phase liquid-vapor flow in the compact pulsating heat pipe (CPHP). The filling ratio (FR) ranges from 25% to 70% during the analysis. [ABSTRACT FROM AUTHOR]

Nowadays, the low-temperature waste heat recovery in the water-dominated geothermal field using the Organic Rankine Cycle (ORC) principle has become an interesting topic. The existing geothermal field with a water- dominated type can be developed an additional power generation without spending the time and cost of exploration. Currently, there are still many types of research focusing on ORC plants to select effective utilization ways. This paper presents the thermodynamic simulation of a small-scale ORC testing facility. The facility mainly consists of a scroll expander integrated with an alternator to generate electric power, an electric heater with thermal oil for representing brine water as a heat source for heating working fluid up to 130 °C in an evaporator, an ORC pump that recirculates working fluid, and a condenser unit as cold sink water at 35 °C. The simulation was performed using the Engineering Equation Solver (EES) as well as the REFPROP external library of thermo-physical properties of working fluids. This study investigates 5 different working fluids of R245fa, R123, R1233zd, n-pentane, and R141b. The performance of the system using each working fluid has been evaluated in terms of thermal efficiency, maximum power output generation, as well as pressure ratio. The temperature of outlet working fluids in the evaporator is simulated in the range of 70° – 130°C with the increment of 5 °C, and the discharge temperature of a condenser is maintained at each temperature of 55 °C, 60 °C, and 65 °C. In terms of maximum power output, R245fa is the best value among other working fluids with a power output of 8.757kW. However, the highest thermal efficiency of 14.17% is achieved by n-Pentane. The highest value of power output doesn't mean related to the performance of thermal efficiency, as a consequence of different characteristics for those properties i.e. density, molecular weight, critical temperature, and pressure. Furthermore, the pressure ratio of almost all working fluids is typically similar by 6.8, unless R1233zd is the lowest among others. Simulation work is examined to understand the effect of different characteristics of various working fluids on the main component's performance system before running at the testing facility. Thus, future works will provide some experiments small-scale test bench and then validate the simulation results. [ABSTRACT FROM AUTHOR]

To improve the performance of an air-conditioning system (A/C) in sub-tropical climates This paper presents an experimental study by studying the double effect of indirect evaporative cooling integrated with heat pipe heat exchanger (HPHE) on sensible heat recovery as well as the coefficient of performance (COP). In this study, HPHE was used consisting of two rows of copper tubes with a diameter of 0.014 m, and length of the evaporator is 0.3 m, the condenser is 0.3 m and the adiabatic is 0.15 m. The results showed that the use of a heat pipe heat exchanger decrease the temperature of air inlet condenser of (A/C) system from (2-3) degree and improves the coefficient of performance by 10 % when compared to conventional cooling systems. HPHE filled with acetone with filling rate of 70%. [ABSTRACT FROM AUTHOR]

In recent decades, adsorption refrigeration systems (ARS) are becoming increasingly popular as one type of environmentally friendly refrigeration system that uses low-grade thermal energy. However, because of its low specific cooling power (SCP) and performance coefficient (COP) compared with the traditional refrigeration systems, it has not been widely commercialized. The present research reviews several methods for improving the SCP and COP of ARS. Several topics related to the performance improvement of the adsorption refrigeration system have been covered such as two-bed ARS, heat recovery, mass recovery, heat and mass recovery, and cascade ARS. This literature review can help the researchers to understand the performance improvement methods for the multi-bed ARS leading to; high COP, lower cost, and shorter charging and discharging cycles times for ARS. Based on the literature review, it can be concluded that raising the temperature of the regeneration and evaporation leads to raising the COP of ARS, whereas raising the condensation temperature lowers the COP. The COP of ARS was about 0.28, 0.26, and 0.25 for MCM-41, silica gel-RD, and silica gel-blue, respectively. The mass recovery cycle enhances the SCP and COP over the traditional cascade cycle. The COP decreases with the increase in the time of the mass recovery. Finally, the heat recovery cycle is suitable for air-conditioning applications. [ABSTRACT FROM AUTHOR]

Air conditioning is one of the most energy-intensive systems which need more attention regarding reduction of energy consumption. The Heat Pipe Heat Exchanger (HPHE) is seen to be a good and cost-effective alternative to reduce the energy consumption. In this work, the numerical simulation of the three-dimensional transient performance analysis was numerically for HPHE and solving by the finite element method through the program ANSYS Mechanical APDL software. Additionally, the theoretical work has been influence study nanocoating with three types of nano metal oxide (CuO, Al2O3, and TiO2) at different nanocoating layer thickness (50, 75, 100, and 125 nm) on the thermal performance of HPHE to enhance the energy saving. The numerical result showed that the improvement of HPHE thermal performance was when the annular fins were coated with CuO at thickness of 100 nm. The improvement in effectiveness, and heat recovery were about 20.36%, and 36% respectively compared to the thermal performance of HPHE without nanocoating on the fins. In addition, it was found from the numerical results that the maximum efficiency level and the heat recovery values were equal to 0.6357 and 1457.42 Watts at the inlet air temperature of 55 °C and the inlet air speed of 1 m/s, respectively. [ABSTRACT FROM AUTHOR]

Several engineering ideas have made use of waste heat recovery methods in recent years. Research in this area focuses on a variety of control and engine management technologies with the overarching goal of improving fuel economy, vehicle performance, and fuel efficiency. This document lays out the plans for using the engine's dissipated heat energy to warm the fuel before it enters the engine to burn. Fuel poured into a fine mist and mixed with air keeps an internal combustion engine going. To prevent engine damage, most internal combustion engines use liquid cooling, which involves either using air, which is a vapour, or a fluid coolant that passes through a heat exchanger (radiator) cooled by air. In an air-cooled motor engine, the goal of the endeavour is to warm the fuel before it reaches the carburettor in order to atomize it more. This study presents an alternative to preheating using engine waste heat, which is advantageous since it reduces strain on the engine and may be used to heat fuel. Vehicles powered by internal combustion engines may benefit from increased thermal efficiency via the use of waste heat from exhaust gases. However, not all exhaust gas heat recovery systems are up to snuff in terms of light temperature and exhaust gas energy. Exhaust gas heat is mostly affected by the combustion phase; spark timing delays have the potential to greatly enhance this heat. At both steady-state and dynamic operating circumstances and engine modes of operation, this study examines how a substantial spark-ignition delay affects heat and exhaust gas. The results showed a remarkable 82.02% gain in fuel economy, which is outstanding but not definitive since the testing were only conducted up to 4500 rpm. Additionally, there was a noteworthy drop in pollutants. [ABSTRACT FROM AUTHOR]

The loss of heat energy from the Internal Combustion Engines are more as compared with the other energy systems. To avoid or utilization of the heat sources are important. In other hand development of semiconductors and the incorporation of the thermoelectric devices are mostly used to avoid the above mentioned statement. In this work the peltier cooling system has been the subject of major advances in recent years and peltier element for CPU cooling, refrigeration, temperature stabilization for peltier cooling with direct energy conversation of heat (thermoelectric generators driven by waste heat, radioactive decay, combustion). In this project, we proposed and built a Peltier-based automatic engine cooling system, which has superior conduction as well as convection thermal characteristics compared to a radiator system. The recommended thermoelectric cooler may replace conventional radiators without requiring additional mechanical components, except for the fundamental elements of the radiator's legacy water-cooling system. They have no sound or vibration and are trustworthy energy converters. In addition to being lightweight and tiny, they also provide more accurate temperature control. The engine's temperature is kept between 18°C and 45°C in this experiment using a Peltier element, temperature sensor, micro-controller, relays, and arduino controller. The typical surface temperature of a central heating radiator in use today ranges from 60 to 90 degrees Celsius, and natural convection contributes more to overall heat transmission than radiative transfer. The use of a thermoelectric cooler (TEC) to increase the heat transfer from the engines to the surrounding air is examined in this research. [ABSTRACT FROM AUTHOR]

The utilization of dissipated heat from the waste heat recovery system is worked out using various potential techniques, considering that an effective and economically compatible technique is heat pipe. This investigation is done along the three heat pipes inserted in the heat exchanger to analyse the performance using different input parameters. The study focus on the tilting of heat pipes for vertical and horizontal inclined angles (0° and 90°), acetone is used for heat pipe operation and similarly water is used for heat supplying and condensing at heat exchanger. The characteristics study makes an observation as 0° angle has highest effectiveness of 60.62%. The influence of increase in effectiveness makes the down trend in thermal resistance meanwhile the performance of the system also increases gradually. [ABSTRACT FROM AUTHOR]

Regenerative heat exchangers are widely used in life support systems, gas turbines, boilers and other high-temperature industrial installations. These heat exchangers are used for cooling and heating gases, humidification and dehumidification of gases, heat recovery from high-potential heat carriers. Today, the increase in energy consumption and the increase in energy prices require a large-scale energy-saving policy in the creation of modern engineering structures-residential, commercial and industrial facilities alike. When designing and creating life support systems to save energy, it is advisable to use secondary energy resources, such as, for example, the heat of the air removed from the room. The energy intensity of conventional ventilation systems is on average 50-80% of the total energy intensity of the engineering systems of the facility where they are operated. The use of rotating regenerative heat exchangers in ventilation and air conditioning systems makes it possible to return up to 85% of heat to the system at a relatively low capital investment. In this regard, when improving such systems, considerable attention should be paid to the calculation, optimization and increase in the efficiency of heat exchangers. Thus, this work is about increasing the efficiency of rotating regenerative heat exchangers in ventilation and air conditioning systems. [ABSTRACT FROM AUTHOR]

The supply of energy needed by human societies is one of the most important issues facing experts due to the increasing technological growth and energy demand. In addition to discovering new energy sources, improving the performance of existing systems is also considered as an effective way to achieve this goal. Among the various methods of improving the performance of power generation systems, heat-waste recovery of power plants is focused by researchers. In this research, five different arrangements of supercritical carbon dioxide cycle have been used as heat recovery of Heydariyeh gas turbine power plant located in Iraq and their effects on the performance of the power plant has been studied. For this purpose, energy and exergy analysis has been used and the performance of these cycles in recovering energy from the heat lost by the mentioned power plant has been evaluated. The results indicate the ability to recover a maximum of 20.8MW of power by supercritical cycles proposed in this study. Indeed, adding this amount of power to the production capacity of Heydariyeh power plant will improve its efficiency by 6.5%. [ABSTRACT FROM AUTHOR]

The performance of evaporative cooling systems depend strongly on the relative humidity of the inlet air. Therefore, it is crucial to reduce the inlet air humidity ratio, and one of the solutions to regulate this ratio is using desiccant material. In this paper, a practical study of an evaporative cooling system was conducted and a dehumidification unit was constructed that consists of a (fin-tube) heat exchanger covered with silica gel to overcome the sensible and latent load. The heat exchanger is connected with an evaporative cooling system and a heat recovery unit as an indirect cooling stage. The cold water in the evaporative basin is utilized for precooling the inlet air. Furthermore, using the cold water of the evaporative basin can reduce the heat released during the removal of moisture from the air (adsorption process). Hot water from a heat source (electrical heater) was used to regeneration the desiccant. The effects of the external conditions (temperatures and humidity) on the system performance were studied. In addition, the effect of inlet air velocity, hot water flow rate, and the time required to complete the cycle on the performance were evaluated. It was found that the desiccant material can be regenerated at a temperature between 45-65 °C and the supply air temperature to the zone of 25 °C when the airflow is 0.48 m3/s. The system can work in hot and humid places. [ABSTRACT FROM AUTHOR]

In this paper, a waste heat dryer unit was built using the condenser of a domestic refrigerator running on R134a refrigerant, which is suitable for drying processes such as fruits and vegetables. The approximate calculations will be addressed to find out the appropriate refrigerator condenser for this purpose. Two types of condensers (L-type and shelf-type) are designed and fabricated inside the drying chamber. Three types of fruits were dried in this experiment: kiwi, apple, and carrot, through natural and forced convection at three speeds (1, 2, and 3) m/s. The effect of airflow on the product was observed, where it was noted that the drying time is less when the heat exchange inside the drying chamber is forced convection, and at the same time, the performance coefficient of the system is slightly increased from 1.7 to 1.83. The drying time for fruit in natural convection was achieved by four hours for (L-type) condenser and five and a half hours for (shelf-type) condenser, while when using a fan, the drying time becomes three hours for (L-type) condenser and three hours and forty-five minutes for (shelf-type) condenser at a speed of 1 m/s. At a speed of 2 m/s, the (L-type) condenser took two hours and thirty-five minutes and the (shelf-type) condenser took three hours and forty-five minutes. And two hours for (L-type, shelf-type) condensers at a speed of 3 m. Comparison between heat rejected from (shelf-type) condenser depending on predicted heat transfer coefficient from air-side with heat rejected from the refrigerant side and the result showed good satisfactory. [ABSTRACT FROM AUTHOR]

The supply of energy needed by human societies is one of the most important issues facing experts due to the increasing technological growth and energy demand. In addition to discovering new energy sources, improving the performance of existing systems is also considered as an effective way to achieve this goal. Among the various methods of improving the performance of power generation systems, heat-waste recovery of power plants is focused by researchers. In this research, five different arrangements of supercritical carbon dioxide cycle have been used as heat recovery of Heydariyeh gas turbine power plant located in Iraq and their effects on the performance of the power plant has been studied. For this purpose, energy and exergy analysis has been used and the performance of these cycles in recovering energy from the heat lost by the mentioned power plant has been evaluated. The results indicate the ability to recover a maximum of 20.8MW of power by supercritical cycles proposed in this study. Indeed, adding this amount of power to the production capacity of Heydariyeh power plant will improve its efficiency by 6.5%. [ABSTRACT FROM AUTHOR]

This paper offers a case study enabling the performance evaluation of the Al-khairat power plant in Karbala city based on the application of the Pinch Analysis (PA) method to determine the best possible heat recovery (Qrec.) available in the plant and how can this be used to minimise energy consumption and save energy. PA has been used to study integration in several processes to help develop optimum heat transfer and minimise total cost: such work has also allowed the development of a Heat Exchanger Network (HEN) design to support this process. Al-khairat power plant consists of 10 units, each of which generates 125 MW; thus, the overall production of the plant is 1,250 MW. Unit 3 was selected as a representative unit for this study, based on its performance stability throughout the year. The data from control room facilities was then used to theoretically calculate the relevant heat loads (ΔH), which were applied in a Composite Curve (CC) to evaluate the Qrec. However, the results suggested that PA may not be effectively applied in this power plant, with similar conclusions being obtained from the application of simulation software (Aspen Energy Analyzer, AEA). [ABSTRACT FROM AUTHOR]

The generation of waste has increased throughout the years of growing industrialization and urbanization. Despite the fact that there are facilities and services that provide treatment, a significant amount of cost must be spent to ensure that the waste is disposed of or treated. This lead to increase the use of Plasma Pyrolysis, Incineration, Anaerobic Digestion, and Gasification to treat the waste while generate energy from the treatment. In order to create a sustainable environment, it is recommended to utilize the waste heat from these processes. In plasma pyrolysis process, there is no additional fuel will be used in treating the waste. The waste heat from plasma pyrolysis will be used to generate power in an Organic Rankine Cycle (ORC) process. However, there is no emerging study has been done on how to generate the electricity from the Plasma Pyrolysis process. The electricity generation from the Plasma Pyrolysis waste heat will be conducted by utilizing the ASPEN HYSYS V10.0 software. Iso-butane and R134a have been determined to have the highest energy efficiency, with highest output powers in between those of other working fluid systems. At a source temperature of 800℃ and pressure 1atm, iso-butane and R134a are observed to have 13.01% and 16.12% energy efficiency, respectively. The R134a and iso-butane fluid gives a better performance in terms of thermal efficiency relative to the other fluids with the maximum power output 2.6190 kW and 2.9320 kW, respectively. This study indicated that the selection of working fluids and the tuning of the operating parameters had a significant potential to improve the performance of the power output of ORC system. [ABSTRACT FROM AUTHOR]

Phase change heat storage materials (PCM) are a class of materials with the ability to store or release a large amount of thermal energy at constant temperatures in the form of so-called latent heat, which is the heat that is necessary to supply or remove from the system to make it change the phase. Due to their energy efficiency, these materials are becoming more and more popular and offer a whole range of practical applications. It is worth mentioning, for example, their use for solar energy storage, waste heat recovery or thermal energy management in buildings [1 – 5]. In the experimental part of this work, we focus on the study of phase transformations and energy accumulation and on the characterization of the thermal properties of new industrial PCMs from the Rubitherm® RT series [10 – 12]. These paraffine wax based materials were developed by the German company Rubitherm Technologies GmbH. Relative thermal conductivity of these materials enables their application even in cases requiring rapid temperature changes and efficient heat transfer, such as systems for cooling electronics or thermal management of batteries. Experiments were performed with three commercially available materials Rubitherm® RT18HC, Rubitherm® RT28HC and Rubitherm® RT35HC. These materials are chemically inert, do not subcool during phase transformations and have a long service life. Materials from the Rubitherm® RT series are available in a full range of different melting temperatures, from −9 °C to 100 °C. For this experiment, materials with melting temperatures of 18 °C, 28 °C and 35 °C were chosen, as their names suggest [10 – 12]. [ABSTRACT FROM AUTHOR]

The examination of thermodynamic equilibrium and solar-to-fuel conversion efficiency of MoO2-MoO based solar thermochemical WS cycle was performed using HSC chemistry v.6.0 software. In this study, the operating temperature and equilibrium compositions required for the reduction step of MoO2, and the re-oxidation step of MoO were estimated. The results of the study revealed that the temperature (TH) required for the 0 to 100% thermal reduction of MoO2 falls in the range of 1800 K¬ to 2409 K. Furthermore, the results indicated the re-oxidation of MoO was favorable at temperatures below 1800 K. The results of efficiency analysis revealed that the solar reactor and steam generator heat input was increased by 2955.38 kW and 159.26 kW with increasing TH from 1800 K to 2409 K and increased the Q_ (solar cycle) by 3114.64 kW. The highest value of solar-to-fuel conversion efficiency (η_(solar-to-fuel)) reaches up to 10.1% with the thermal reduction of MoO2 increasing from 5% to 100% without heat recuperation. However, with 20% and 50% heat recovery, the highest conversion efficiency reaches up to 10.33% and 10.95%, respectively. [ABSTRACT FROM AUTHOR]

A compressor in a rice manufacturer, PT. X, got overheated especially on hot days. The overheat makes the compressor shut off and stops the production line. From the observation and data collected in PT. X, it was found that the overheat problem in the compressor was caused by [1] the dust on the surface of the aftercooler and the fluid cooler, and [1] the high temperature of the intake air to the compressor. The management comprehends the suggestion to clean the coolers' surface, close the door to the compressor room, and install an intake duct to bring in cooler air input to the compressor. Carrying out the suggestion, the overheat problem is overcome and there is saving in operational cost. The savings could be more than 4000 kWh/year for eight hours of work each day. By lowering the inlet air temperature as much as 4C° for the compressor, the CO2 emission could be reduced around 4000 kg/year. A heat exchanger could replace the after cooler and the fluid cooler for recovering the waste heat of the compressor. The heat to be recovered from the compressor is approximately 40 kW. The waste heat recovery framework will produce 13 liter/min water at 70°C. [ABSTRACT FROM AUTHOR]

Refrigeration system plays a crucial role in the dairy sector to preserve quality and prevent spoilage of milk. This sector also have enormous heating requirement for various processes such as pasteurization and heating of water for cleaning. The carbon dioxide (CO2) based refrigeration system is perceived to be an excellent choice for dairy application since it can simultaneously meet the cooling and heating demand. In the present study, a novel ejector based CO2 transcritical refrigeration system with integrated mechanical subcooling (IMS) is proposed for dairy applications. With IMS, the heating capacity of the refrigeration system is improved since the heat removed for subcooling can also be rejected into the heat recovery unit. The proposed system chills milk to 4 °C and simultaneously supply heat to water that can support various heating requirements. A parametric analysis of the proposed system is carried out and the results are analysed to comprehend the effect of ambient temperature, gas cooler pressure, effectiveness of the heat recovery heat exchanger and degree of subcooling on various performance parameters. It was found that the proposed system could heat water up to 80 °C and achieve an overall coefficient of performance of 4.15 at an ambient temperature of 40 °C. The study concludes that the proposed system is an energy efficient and clean alternative to conventional refrigeration and heating systems. [ABSTRACT FROM AUTHOR]

In the present scenario of thermal management system, the cooling efficiency is one of the crucial factors to enhance the performance and life of the heat generating devices. In single phase mode it is very difficult to achieve large heat recovery. So, two phase mode is best suitable method to recover large quantity of heat from the heat sources. Nuclear reactor, electronics cooling, air conditioning system etc., are employing two phase heat transfer for efficient heat recovery. To analyze the heat transfer, the passive technique is more suitable because of less energy consumption. Instead of using conventional fluids for heat transfer, employing nanofluid is an emerging technique in the current heat transfer technology. In the present investigation, a hybrid nanofluid is prepared for 0.6% volume concentration from Al2O3 and SiO2 at equal volume fraction. An experimental investigation was conducted in pool boiling with novel hybrid nanofluid, the safety and performance characteristic were analyzed. [ABSTRACT FROM AUTHOR]

In the analysis of overall distillation column costs, energy usage has become the most essential element. Many researchers have focused on the development of external heat integration systems, such as heat pump assisted distillation, due to excellent performance in reducing net energy requirements. In regards to our previous works on this subject which showed only 50% of energy reduction, optimization might result in further energy saving. Therefore, this study intends to incorporate a two-step optimization procedure to the VRC-assisted column model for the fractionation of PKO fatty acid. The procedure includes the sensitivity analysis using Aspen Plus which went hand in hand with response surface methodology (RSM) using Design Expert. The optimal solution obtained from the RSM was validated in Aspen Plus to ensure model convergence. The superheated temperature and compression ratio were selected as the predominant factors to the exchanger duty. The model was found to be statistically significant, owing to its small p-value of <0.0001. The large R2 value of 97% suggests that the model was highly reliable in predicting the exchanger duty, which was proven from the small residual percentage of 6.14%. The given optimal point showed an increment of 27% of heat recovery from the top vapour stream. Though the results seemed appealing, the simulation of the optimal points in Aspen Plus revealed that the maximum allowable operating temperature was deviated. [ABSTRACT FROM AUTHOR]

This work is motivated by the modelling a liquid-vapour flows with phase transition describing the evolution of the coolant within an heat exchanger (e.g. the core of a Pressurized Water Reactor). We investigate an advection-diffusion equation with a degenerate and nonlinear diffusion coefficient. The degeneracy corresponds to a liquid-vapor mixture in the original model whereas the diffusion coefficient is non-degenerate in the pure phase cases. We focus on the influence of the diffusion coefficient on a simple 1D configuration for which some analytical computations can be done, leading to a surprising behavior of the phase transition with respect to the diffusion. [ABSTRACT FROM AUTHOR]

Waste heat from Air Conditioner (AC) is neglected as a heat source for power generation due to its low temperature. In today's world, the demand for energy has increased, but the amount of energy that is available is less. Also, there is no viable option for effective utilization and energy conservation. This paper feature design and analyze the waste heat recovery system. The waste heat taken from the outlet of an AC condenser is concentrated and converted into electricity using Thermoelectric Generator (TEG) modules connected in a series-parallel combination. A duct made of an aluminium sheet is used to concentrate waste heat because it has a high absorption point. The data in terms of temperature, voltage, and current is sensed, measured, and analyzed under different scenarios with and without the concentration of heat radiation. After analyzing all the different combinations, the most efficient one is chosen. With the presence of an aluminium duct concentrator, the temperature increased by 28%. When tested with TEGs, with water at ambient temperature and an ice pack on its cold side, the temperature gradient increased by 40%, resulting in an increase in voltage of around 80%. Three sensors, a DS18B20 temperature sensor, a voltage sensor, and an ACS712 current sensor, were connected to collect real-time data from the waste heat recovery system, and an ARDUINO UNO interface was used to record and analyze the bulk data. Graphical illustrations are provided for analysis, and to improve the voltage and current output as per load demand, a power electronic converter unit is suggested to boost the voltage level. [ABSTRACT FROM AUTHOR]

Wastewater in a houseboat facility contains a large amount of heat energy that is irretrievably lost, so it is worth considering the possibilities of its recovery. It is estimated that in a typical residential building with full sanitation, approximately 70% of the total tap water supplied is discharged as gray water and can be reused. Heat recovery from wastewater can be carried out in many ways, it is influenced by various factors, including the location of the heat collection point from wastewater. The wide range of available technologies means that the market is full of many original and interesting solutions. The subject of the work is the possibility of recovering heat from wastewater as an alternative energy source for heating domestic hot water. The article presents an overview of solutions used in practice on the market, with particular emphasis on the possibility of their application in a houseboat facility. The article practically verifies the selected recovery system on a local scale (point recovery) at the selected facility-the so-called Drain Water Heat Recovery (DWHR). In the scope of analyzes, an original simulation tool was used, allowing to verify the effectiveness of the applied solution for various design and material variants of the exchanger. The conducted analyzes and simulations show that local systems of heat recovery from gray water allow for significant savings in the scope of heating domestic hot water, and the potential rate of return depends on the purpose of the facility and the type of installation. At the same time, the research shows that the design solutions of heat exchangers and internal installations in the analyzed facility in the form of a floating house (houseboat) should be adapted to the energy parameters of the flowing medium, which are the so-called gray waters. [ABSTRACT FROM AUTHOR]

Energy-saving measures in the design, construction and operation of buildings are mainly due to the reduction in the reserves of mineral raw materials and fossil fuels and, as a result, their constant rise in price. A schematic diagram of energy-saving measures in the water supply system of a residential building is presented, where cold water is heated by means of disposal from waste water, which is intended for supply to the hot water supply system. A schematic diagram of a technical solution for an energy-saving hot water supply system for a seventeen-story residential building has been developed. The article considers the possibility of utilizing the heat of relatively clean effluents discharged into a separate drainage riser and a conventionally named "gray" effluent. The most polluted part of the wastewater is removed by a parallel drain riser with the code name "black" drain. A schematic diagram of heat recovery from the "gray" wastewater of water disposal systems for preheating cold water supplied to the heat exchangers of the first and second stages of hot water supply is proposed. The use of a three-stage heat supply scheme for a hot water supply system with heat recovery from "gray" wastewater reduces the amount of heat for heating hot water by 9.1%. The use of a three-stage hot water heat supply scheme implies additional capital costs, the payback period of which, taking into account the discounted cost, is up to 3.5 years. An analysis of the economic feasibility of using the proposed wastewater heat recovery system for preheating cold water of the hot water supply system of a residential building was carried out. [ABSTRACT FROM AUTHOR]

Various options for the location of fans in an air handling unit (AHU) with a rotary regenerative heat exchanger are considered. A method for calculating leakages between the supply and outgoing channels is proposed. The systems of linear algebraic equations for the balance of air flows, heat flows and pressure drops in the heat exchanger for three layout schemes are presented. A computational study of the effect of gaps in sealings on the coefficient of heat recovery of outgoing air and leakage between AHU channels was carried out. Recommendations are given for the design of regenerative heat exchangers, taking into account leakages between the supply and outgoing air channels. [ABSTRACT FROM AUTHOR]

The development of methods for solving inverse heat conduction problems over time becomes more complicated with a variety of batteries transformer of unsteady heat flux by type and variety of structures, thermal and measuring circuits. The parametric identification of differential-difference models is considered, which take into account various nature of the external influence and the processes occurring in the systems of bodies. The solution was carried out in a standard way using the transition matrix of the system state, which allows obtaining the corresponding temperature values at any time from the initial values of the temperature of each part of the body. A method for establishing a trust region during the restoration of heat transfer parameters is considered. A distinctive feature is the general approach to compiling a differential-difference model of heat transfer for various systems of bodies. [ABSTRACT FROM AUTHOR]

Waste Heat Recovery Power Generation (WHRPG) technology is a technology that produces electrical energy from the flue gas from the operation of a cement factory that releases CO2 and converts it into electrical energy in the cement industry. Utilization of the generated electricity can be used as a supply of factory electricity needs such as lighting, equipment and various other facilities. Since 2014-2017 until now the operation of the WHRPG in the tuban factory after several times setting hot gas on the conversion system only able to produce electricity capacity of 28.6 MW is still far from the planned capacity target, this requires the right operating strategy in order to achieve electrical energy capacity 30.6 MW. Efforts to increase the production capacity of electricity generation from the utilization of hot flue gas in terms of engine performance readiness aspects of steam power plant technology need to be carried out operational planning and maintenance using the Inspection, Small Repair, Medium Repair and Overhoul (ISMO) implementation method through Total Productive Maintenance. (TPM) technical repairs on WHRPG power plant equipment such as damage to pumps and hot gas settings in boilers and other components are repaired in order to get better performance so that the energy produced can reach 95% at the performance ratio value from the predetermined initial capacity. It is known and can be improved on the value of OEE (Overal Effectiveness Equipment) by implementing total productive maintenance on all power generation equipment so that the combination of production and maintenance together can increase the production of 30.6 MW of electrical energy can be realized. [ABSTRACT FROM AUTHOR]

The organic Rankine cycle (ORC) is proven to be one of the environmentally friendly approaches in improving energy generation, waste heat energy recovery, and medium-low-temperature heat utilization. Waste heat recovery and low-grade heat utilization are important measures to solve the problem that occurred from energy consumption. Working fluid plays an important role in the performance of ORC. This study conducted a quick literature review on the working fluid selection for the ORC system. This brief review analyzed the influence of working fluid category, thermodynamic properties, and physical properties as well as the relevant limitations on the performance of ORC. The safety level and environmental aspect of common working fluids for ORC were also reviewed. The findings indicate that R11, R141b, R113, R123, R124, R600, and R601 have slightly higher performances but R600 are flammable. However, R245fa is the most environmentally friendly working fluid for waste heat recovery applications. In this study, the working fluids selection criteria for the ORC system have been reviewed. This study helps in identifying the potential organic fluids for various ORC applications especially in waste heat recovery from low-temperature heat sources. [ABSTRACT FROM AUTHOR]

The article shows the possibility of using the technology of recycling of secondary energy resources (SER) of the organic Rankine cycle (ORC). The perspective developments in the field of waste heat development due to the introduction of the ORC at the boiler houses of the transport infrastructure, ship installations are analyzed. The aspects that complicate the widespread introduction of a specific technology into the heat economy of stationary and mobile power facilities are identified: high weight and size characteristics of heat exchange equipment. It is shown that the solution to this problem lies in the construction of detailed methods of mathematical modeling. An increase in the detail of the mathematical model is possible mainly due to the use of specialized software systems in the calculations. In addition, refinement of existing analytical methods is equally capable of adjusting model building. The paper compiled a methodology for preliminary mathematical modeling of condensing equipment using the engineering complex NIST REFPROP DATABASE Version 8.0. The specified program has a wide range of tools for the thermophysical properties of working bodies and with its help; it is possible to supplement the above technique. Based on the above factors, it can be concluded that with a more detailed analysis of the problems of integration of ORC converters, they can become a very promising technology for heat recovery. [ABSTRACT FROM AUTHOR]

Stoves with wooden fuel are widely used by communities in developing countries. Despite the relatively low efficiency of wood as fuel in stoves, the heat released could be reused and/or harvested into electrical energy. This work applied the Thermoelectric Energy Generator (TEG) technology to harvest the heat energy surrounding the stove into electricity by installing the TEC1-12706 and SP1848-27145SA cells in the upright position on the stove. The potential thermal energy efficiency of biomass stoves with an attached TEG was calculated. The results showed that when two TEGs in pair were attached, 1.48 V and 0.09 A were produced, meanwhile when the round side of the stove wall was fully attached to TEGs, it showed potential electrical energy production up to 0.27 W. The amount of energy produced was able to recharge lithium-ion batteries for 53 minutes using a buck-boost DC voltage converter, also contributing to increasing the stove's energy efficiency by 0.014%. [ABSTRACT FROM AUTHOR]

This article discusses one of the most typical heat-using processes - the drying process. The selection and assessment of drying units are carried out according to various parameters; however, the clearest idea of the suitability of the dryer for drying material with known properties and its energy characteristics is given by the analysis of the dryer operation, based on the heat technology principles of the design of the technological process under which a characteristic set is taken thermal, hydrodynamic, constructive and other conditions for organizing the technological process of drying materials. Comparison of the energy efficiency of several dryers, carried out according to the described technique, taking into account the costs of creating and maintaining the required hydrodynamic conditions in the working chamber of the drying apparatus, referred to the unit volume of the chamber, taking into account the separation of the dried material and cleaning the spent heat carrier. [ABSTRACT FROM AUTHOR]

The objective of this study is to evaluate the current boiler performance in a tire industry and to identify areas where improvements can be made based on energy conservation opportunity (ECO). ECO can be performed in various ways, including applying O2 trimming, installing an economizer, implementing blowdown heat recovery system and insulating the condensate tank & pipelines. This study was conducted on three boilers, in which Boiler 03 was a backup boiler without an economizer. The efficiency of the three boilers was calculated using the indirect method according to BS 845-1:1987. The current boiler efficiencies were about 79% for boilers with economizer, and 74% for boiler without economizer. The recommended ECO would give gas bill cost-saving in the range of 0.47 – 1.4% (Rp 18.6 – 36.8 million/month). The investment range would be Rp 400 million – 1.2 billion with simple payback period of 1.2 – 2.7 years. The first priority of ECO mentioned above should be the installation of an economizer with a cost-saving up to Rp 30.2 million/month, which gives a simple payback period of 1.2 years. [ABSTRACT FROM AUTHOR]

Several tries square measure being created everywhere the planet so as to form power-generator engines with acceptable potency and with the potential ofi exploitation waste heat recovery and renewable energy sources at identical level because the fossil fuels. Use ofi non-renewable energy sources ofi thei world as well as oil, gas and coal destroys the societies' public wealth and produces twenty-five percent ofi thei whole dioxide of the planet. The Sterling engine is an external combustion engine whichoperates on Sterling cycle. It operates on a closed cycle, so there is no need of using the fluid again and again as in case of other power plants. Due to this usage of non-renewable energy sources for production of power are not needed and also there is noproblem of pollution because there are no emissions from the engine. The Sterling cycle efficiency is nearer to Carnotefficiency. But it was come into usage dueto difficulties in design of regenerator up to last 19th century. But due to developments in material science, this problem has been overcome in 20th century. The cost of the engine is high, but due to its higher efficiency and no emissions, priority for this engine for production of power is increasing. The radiation may be centred on to the hot-end ofi thei Sterling engine, thereby making a solar-powered causal agency. The direct conversion of alternative energy into mechanical power reduces each the value and complexness of the causal agency. In future, may be Sterling engine with solar energy as heat input will be a better power generation method. [ABSTRACT FROM AUTHOR]

Incorporation of a heat recovery heat exchanger in the ventilation system in cold climates reduces the requirement of external energy for heating. However, frost formation can be an issue. In this work, a model of a counterflow heat recovery heat exchanger with frost formation is implemented using Matlab/Simulink. The model is used to study some representative conditions. The results show that the model predicts heat recovery as well as ice formation. After further refinements and validations, the model can potentially be used for predicting frost formation. [ABSTRACT FROM AUTHOR]

Solid desiccant based rotary wheel with components like heat recovery wheel, evaporative cooler and a heater or generator, combined known as solid desiccant cooling system (SDCS), provides an alternative cooling system which can be a better solution to achieve the desired cooling comfort, especially in hot and humid climate. In this paper, the effectiveness of this system was evaluated in terms of COP. Results obtained from the simulations were used to find out the COPs. TRNSYS version 16 software was used in this analysis. COPs of this system for a lecture theater, for which cooling comfort is be achieved, were calculated under different climatic conditions. In this regard, four major cities of India Trivandrum, Kolkata, Mumbai and New-Delhi were selected. The calculated values of COPs show that SDCS works very effectively in the hot and humid climate. [ABSTRACT FROM AUTHOR]

This work belongs to a cycle of scientific research related to a promising direction for improving aviation turboshaft engines through the use of heat recovery and determining the optimal parameters of the working process of such engines at the conceptual design stage. Joining recuperators in the aviation gas turbine engine industry shows a significant opportunity for reducing emissions and fuel consumption. Rational choice of parameters of turboshaft engines is a necessary condition for its successful design to increase the efficiency of the engine consequently the focus of the article was on the mathematical setup for problem optimization and the selection of rational thermodynamic cycle parameters for turboshaft engines with recuperators. In this paper the flight-technical and transport - efficiency optimization criteria are selected for optimizing the thermodynamic cycle parameters of turboshaft engine with recuperator. A complex mathematical models describing the engine operation in the ANSAT helicopter system has been developed and applied. The simulations mathematical models of the transport helicopter flight cycle was implemented to solve optimization problems at the stage of a conceptual design in the machine program tool. [ABSTRACT FROM AUTHOR]

This Paper is devoted to the analytical investigation of Triple Net Zero Building energy consumption for climate conditions of Dnipro, Ukraine. The results are based on a nZEB construction literature survey, and case study. The obtained data reveal that the specific energy consumption of 9.64 kWh/m2 does not exceed the standard of the Passive House Institute of 15 kWh/m2. The energy consumption for cooling is only 0.4 kWh/m2 thanks to the use of the ventilation system with local heat recovery equipment in each room. This leads to the energy consumption of the ventilation system in the amount of 1.2 kWh/m2. The energy consumption of the building for DHW production is 8.73 kWh/m2. The energy consumption of the building for lighting is 9.69 kWh/m2. Therefore, the total energy consumption of the building will be 29.66 kWh/m2. The indicated result is approximately twice less than the maximum according to the Passive House Institute standard – 65 kWh/m2. [ABSTRACT FROM AUTHOR]

Waste or recoverable heat is a resource that could be cost-effectively exploited by district heating (DH) systems to increase the efficiency of heat supply in buildings. This paper introduces the Bunhill waste heat recovery (WHR) system, a novel scheme that recovers waste energy from a ventilation shaft of the London Underground (LU) transport network. The system is based upon the installation of a heat recovery heat exchanger consisting of cooling coils and a reversible fan; the coils are connected to a heat pump that supplies low-carbon thermal energy to the Bunhill DH network in central London. One particularly important aspect of the Bunhill WHR system is its ability to operate in a way that not only provides heating to the local heat network, but can also simultaneously supply cooled air to the LU tunnels depending on the operation of the reversible fan. The current paper presents the results from an investigation into the benefits of integrating heating and cooling from the perspective of reducing carbon emissions and the levelised costs of energy from the WHR system, whilst also alleviating peak temperatures at nearby LU stations through the cooling provided. The findings of the investigation are presented together with recommendations for further development and future deployment of WHR systems, which not only apply to underground railways but also to other sources of recoverable heat. [ABSTRACT FROM AUTHOR]

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As a member of the European Union, Romania must take measures to reduce CO2 emissions, in order to achieve the objective of Europe becoming the first neutral continent in terms of controlling carbon emissions. The paper analyzes the influence of ventilation systems with heat recovery in the process of dimensioning the heating systems related to buildings, both from the perspective of the calculation of heat requirement for sizing the equipment and the annual energy requirement for charging. The analysis simulates the thermal calculation for a newly designed construction, according to SR 1907 and C107, in order to reduce CO2 emissions according to Green Deal principles. [ABSTRACT FROM AUTHOR]

The article discusses the new in Uzbekistan heat recovery technology is leaving the flue gas from boilers. This is achieved by condensation of water vapor therein. An analysis of the advantages and disadvantages of contact heat recovery and surface types. The results of monitoring of the heat capacity of these plants to the Russian and foreign heat power plants (HPP). The analysis of the heat transfer coefficients in the condensing heat exchanger surface. The temperature regimes which provide point of the flue gas dew point. The limited stresses in the chimney of the boiler unit are calculated using condensing heat utilizers of the exhaust gas for stations of Uzbekistan [ABSTRACT FROM AUTHOR]

In any processing facility, the cost of production is critical and will determine whether it remains operational, as high production costs affect its viability. In the case of a ginger processing facility, one major cost is the burning of gas to provide thermal energy to its dehydrator. Research shows that the temperature and humidity of the air in a dehydrator will affect the rate at which a food product is dried. A reduction of 30% in the humidity level of the air can reduce the drying time by 64% for certain food products. In this project, potential modifications for an existing dehydrator are evaluated to determine whether they will improve the overall performance and efficiency of the dehydrator and reduce the amount of energy required to dry the ginger. These potential modifications include incorporating a desiccant dehumidification wheel and a waste heat recovery system to improve the performance of the dehydrator. Apart from removing moisture from the air, the desiccant wheel also transfers thermal energy to the inlet air during the dehumidification process. The detailed model is developed using TRNSYS simulation software, and key component results are validated with experiments. Modelling shows that the combination of a desiccant dehumidification wheel and a heat recovery system can reduce gas consumption by approximately 77%. However, other factors also need to be considered to maximise the improvements in efficiency and performance. [ABSTRACT FROM AUTHOR]

The objective of this research work was to improve the energy efficiency of a traditional hot air food dryer using the waste heat recovery technique. A crossflow heat exchanger was installed at the exhaust vent that used waste heat from the dryer exhaust air to boost the temperature of the intake air. The amount of the exhaust air at the temperature of 100 °C was between 0.017 to 0.033 kg/s. From the results obtained, it was evident that the flow rate of the exhaust air directly affected performance in terms of efficiency and effectiveness of the heat exchanger. When both parameters were increased, the performance of the heat exchanger improved accordingly. In the case of recovering 100% recycled humid air, the efficiency and effectiveness of the heat exchanger used in this research reached a maximum of about 74% and 51%, respectively. As a result, the electrical power consumption of the dryer was reduced by 0.71 kWh, which accounted for an energy saving of almost 24%. Installation of the crossflow heat exchanger was found to enhance the temperature of the dryer's intake air by approximately 35% and the dryer's efficiency by more than 28%. [ABSTRACT FROM AUTHOR]

The article analyzes the problem of energy conservation in the context of organizational and technical measures. One of the conditions for energy saving is the use of waste energy. Heat recovery during energy production in technological systems is considered. The characteristics of energy resources with the identification of the main parameters are given. The problem of energy recovery in various technical objects through recovery devices is studied. An adequate definition of internal energy resources is given. Sources based on the generated energy (waste energy sources) are described. The factors inhibiting the use of waste heat at industrial enterprises are considered. The absence of a consumer of recycled energy is cited as an important reason. An analysis of the economic efficiency of various fuel economy measures has been carried out. The estimated data on various parameters of energy saving in various industries are given. The role of the economic crisis, which reduces the volume of production and consumption in the world, is highlighted. The analysis of technological heat supply schemes is carried out. The conclusion is made about the effectiveness of steam ejector circuits. [ABSTRACT FROM AUTHOR]

The paper considers the application of an experimental-computational technique for determining the empirical coefficients necessary to determine the characteristics of active heat utilizers of exhaust air heat under arbitrary operating conditions. The design of the stand for testing active heat recovery units is described. A test procedure and expressions for calculating the necessary empirical coefficients are presented. [ABSTRACT FROM AUTHOR]

This article describes the methodology of technical and economic evaluation of active heat exchangers. The technique is designed to assess the energy characteristics of active utilizers operating in conditions that differ from the passport values. The influence of deviation of such operational factors as air consumption, outdoor temperature in front of the utilizer, temperature, and humidity of the exhaust air is considered. The method takes into account the operating mode in-volving the heating of the external air before being fed into the room without affecting the air-cooling mode in the warm season. Coefficients of renewability and economic efficiency are proposed as criteria for comparing active and passive heat recovery devices. The proposed criteria make it possible to evaluate the efficiency of using recycling systems both in energy and in financial terms. [ABSTRACT FROM AUTHOR]

Development of micro ORC systems with 1-15 kW power output for micro-cogeneration and waste heat recovery at the Czech Technical University in Prague, University Centre for Energy Efficient Buildings (CTU UCEEB) has over ten years of history with many successes. These include 6 different ORC units, all with in-house designed rotary vane expanders (RVE) of many versions throughout this development. Among main advantages of the RVE belong relatively simple and robust design at low cost even at very small series of single-unit production and all that with acceptable efficiency. The ORC units operate with hexamethyldisiloxane (MM) working fluid at high pressure ratios and expansion ratios and the isentropic efficiency of RVE has a limit at these conditions around 60%, often however only at values around 50%. While this might be enough on a cost side for commercialization of this technology, in pursuit of higher efficiency solutions, different expander technology needs to be selected. A turbo-expander is a logical choice with prospect of higher efficiency. At the same time, a literature review has found a lack of reported detailed experimental data for micro (5-50 kW) turbo-expanders, possibly hindering global development towards economically feasible solutions. A project named Dexpand, "Optimised expanders for small-scale distributed energy systems" aims at these issues by objectives in designing, optimizing, manufacturing and testing several ORC expanders with MM and isobutane and their subsequent performance mapping and comparison. One major task is a design of a turboexpander for a 120 kWth biomass fired microcogeneration ORC unit currently operated at the CTU UCEEB. An axial impulse single stage turboexpander was selected as a suitable choice, providing a prospect of a decent efficiency at technically manageable rotational speed and size. This paper provides a detail of currently performed design activities, starting from boundary conditions specification, over development and optimization of a 1D model, preliminary 2D CFD calculations and finishing in a state of a robust and detailed 3D CFD model with a real gas model. Note that the working fluid, high molar mass organic vapour, is highly non-ideal in its behaviour and the flow conditions with pressure design ratio around 13 is highly supersonic (nozzle outlet isentropic Mach number exceeds 2). The current results based on 3D CFD indicate a prospect of an isentropic efficiency 71% at mechanical power output of 11 kW. Lastly, ongoing and future work is outlined, which includes aerodynamic optimization based on the developed 3D CFD model and construction design of the entire turbine assembly. [ABSTRACT FROM AUTHOR]