Conventional Heat Sources Research Articles

On the possibilities of solar energy usage for heating single-family houses in Poland

The paper presents an assessment of the possibility of using solar energy for heating a selected residential building. The influence of the thermal insulation standard of the outer casing and the air tightness of the building on technical solutions with conventional heat sources and a solar energy system was analysed. In Polish climate conditions, especially in November and December, the availability of solar energy is usually insufficient in relation to heating needs. Therefore, it is necessary to store heat when it is to be used for heating. Monthly and yearly periods of heat storage have been considered. The influence of the use of solar radiation energy on the change in the energy performance of the building and on the reduction of carbon dioxide emissions was determined. Characteristics of heating systems and devices [9] as well as generally available meteorological data [5] were used for energy calculations.

Microwave-assisted heating: innovative use in hydrolytic forced degradation of selected drugs

ABSTRACTStress testing has been executed to illuminate the inherent stability characteristics of drug substances and drug products. As an alternative to the conventional hydrolytic forced degradation, which is carried out at the elevated temperature for an elongated time period, microwave-assisted heating is believed to be more promising. The later technique offers many advantages over conventional heating technique like fast, efficient heat source, a more reproducible result due to the control of parameters, eco-friendly, unlike conventional heating source, it heats up only the molecules which absorb microwave energy and not the apparatus first. Present work reports microwave-assisted hydrolytic degradation studies of selected drugs, namely Lurasidone, Risperidone, Paliperidone, Alprazolam, Escitalopram, Atomoxetine, Repaglinide, Furosemide, Hydrochlorothiazide and Olmesartan. The degradation samples were analysed by using high-performance liquid chromatography techniques. The degradation products generated by conventional and microwave heating methods were compared with respect to relative retention time. Though selected drugs have different chemical structures, the unaltered degradation profile was observed when conventional heating was replaced by microwave heating. With the proposed microwave heating technique, degradation products were generated in drastically lesser time from many hours to minutes without generation of secondary degradation products.

Domestic heat generation and distribution with time-variant receding horizon control

Modern domestic heating systems combine conventional heat sources with more advanced devices such as heat pumps or energy storages. Due to the existence of multiple sources and sinks, the question arises, how to operate these systems in an economically optimal fashion. It is natural to pose this question as an optimal control problem that is solved on a receding horizon, where the receding horizon allows to account for periodically updated predictions of the heat demand and energy prices. These periodic updates imply, however, the optimal control problem has time-variant constraints and a time-variant cost function. We demonstrate the resulting receding horizon optimal control scheme can be solved and optimizes the heat flows in a domestic heating system that comprises a heat pump, a thermal storage and an auxiliary heater. Our results show the predictive controller is able to anticipate and compensate for heat shortages due to heat pump blocking times.

Microwave-assisted pyrolysis with chemical activation, an innovative method to convert orange peel into activated carbon with improved properties as dye adsorbent

Microwave-assisted pyrolysis with chemical activation was developed and optimized to transform orange peel into activated carbon (AC) desirable for use as a dye adsorbent. The orange peel was first carbonized via microwave-assisted pyrolysis to produce a biochar, which was then activated and converted into AC via chemical impregnation coupled with microwave-assisted pyrolysis. The process parameters involved was optimized to maximize the yield of AC and its adsorption efficiency on malachite green dye using response surface methodology adopting central composite design. The use of microwave-assisted pyrolysis provided a fast heating rate and short process time in converting orange peel into AC, recording a heating rate of up to 112 °C/min in a process taking about 25 min, representing a method that is potentially faster and more energy efficient compared to that shown by the method commonly performed using conventional heating source (≥1 h). The results showed that AC with the highest yield (87 wt% of biochar) and optimal adsorption efficiency (28.5 mg of dye/g of AC) can be obtained by performing chemical impregnation at an impregnation ratio of 1:1 coupled with microwave-assisted pyrolysis under microwave irradiation (heating) for 5 min using 550 W of microwave power. The addition of chemical activation with alkali metal hydroxides resulted in the production of AC with improved properties. The AC showed a highly porous structure containing high content of fixed carbon (83 wt%) and high BET surface area (1350 m2/g). The adsorption–desorption isotherm showed a combination of Type I and Type II isotherms, which indicates the presence of microporous-mesoporous structure, thus exhibiting a characteristic of improved pores accessibility and high adsorption capacity. Combined with the detection of low ash (3.2 wt%) and moisture content (5 wt%), the AC shows great promise as a high-grade dye adsorbent with high adsorption capacity and potentially increased durability since a low moisture content could increase the rate of adsorption of dye contaminants and a high ash content could promote undesirable catalytic reactions and reduce the adsorption capacity and reactivation efficiency of AC. The recovery of AC with improved properties and the desirable process features (fast heating rate, short process time) suggest the great potential of this method as an alternative for the treatment and recovery of fruit peel.

Energy and economic optimization of the repowering of coal-fired municipal district heating source by a gas turbine

One of the possible solution for conventional coal-fired heat sources of district heating systems is repowering with a cogeneration of heat and power) unit. Thermal and economic optimization of the such modernization is the subject of the paper. The total capacity of the existing heat generating plant reaches 210MW and the generated heat is delivered to the city consuming central heating and hot domestic water. The optimization of the cogeneration system (regarding unit size) was aimed at finding a solution which is an optimal in terms of the economic efficiency.The optimal size of gas turbine was found and it has been proven that the retrofitting coal-fired district heating source with a gas turbine cogeneration unit has technical and economic justification and always leads to the energetic and ecological effects. However, the optimal size of the unit is highly sensitive to electricity and natural gas prices.

Plasmon heating mediated Friedel-Crafts alkylation of anisole using supported AuNP@Nb2O5 catalysts

Two different hybrid materials composed of gold nanoparticles (AuNPs) supported on either commercial niobium oxide HY 340 or mesoporous niobium oxide catalyzed the Friedel-Crafts alkylation of anisole by benzyl chloride. Excitation of the surface plasmon of the supported AuNPs allowed the reaction to occur at lower temperatures by acting as an alternative heat source. The localized heating produced via plasmon excitation permitted the acid catalyzed reaction to occur - at the Lewis acid sites on the Nb2O5 support - at 80°C while thermal-dark reactions using a conventional heat source, required temperatures of 120°C or higher. The catalytic activity of the tested hybrid materials decreased with storage time. However, the deactivation showed to be reversible upon lyophilisation indicating that the nature of the deactivation could be due to water adsorption.

Groundwater source heat pump application in the heating system of Tibet Plateau airport

Due to the lack of conventional energy and fragile ecological environment in the Tibet Plateau at an elevation of over 3000m, renewable energy utilization is of great significance in environment protection and energy conversation. A field measurement of a groundwater source heat pump (GWSHP), a part of a solar assisted GWSHP heating system of an airport in the Tibet Plateau with the side of solar collectors broken down was conducted in this paper. Meanwhile, the indoor thermal environment in the terminal and dormitory heated by radiant floor was measured. The performance, economy of the GWSHP and indoor thermal environment were analyzed. At last, a comparison between the GWSHP and other heat pumps used in this region was made. The results showed that the coefficient of performance (COP) is about 5.0. Compared to conventional heat sources, the performance of the GWSHP is optimal in regard to both energy conservation and economic efficiency. There was a significant difference observed between the thermal environment in the terminal and dormitory. Accordingly, design considerations and regulation measures are recommended to improve the thermal environment. Compared with heat pumps used for heating in the Tibet Plateau so far, the GWSHP in this paper is better.

Nonuniformity of Temperatures in Microwave Steam Heating of Lobster Tail

The biennial Conference for Food Protection provides a formal process for all interested parties to influence food safety guidance. At a recent conference, an issue was raised culminating in a formal request to the U.S. Food and Drug Administration to change its Food Code recommendation for safe cooking of seafood using microwave energy when steaming was also employed. The request was to treat microwave steam cooked seafood as a conventionally cooked raw animal product rather than a microwave cooked product, for which the safe cooking recommendation is more extensive owing to the complex temperature distributions in microwave heating. The request was motivated by a literature study that revealed a more uniform temperature distribution in microwave steam cooked whole lobster. In that study, single-point temperatures were recorded in various sections of the whole lobster, but only one temperature was recorded in the tail, although the large size of the tail could translate to multiple hot and cold points. The present study was conducted to examine lobster tail specifically, measuring temperatures at multiple points during microwave steam cooking. Large temperature differences, greater than 60°C at times, were found throughout the heating period. To compensate for such differences, the Food Code recommends a more extensive level of cooking when microwave energy, rather than conventional heat sources, is used. Therefore, a change in the Food Code regarding microwave steam heating cannot be recommended.

Role of morphological characteristics on the conductive behavior of LaNiO3 thin films

LaNiO3 (LNO) thin films were synthesized via the polymeric precursor method and sintered using conventional and microwave heating sources. The samples were characterized by structural morphological and electrical techniques. The crystalline structure was analyzed by X-ray diffraction and indicated rhombohedral perovskite phase in both films sintered using conventional and microwave heating. The films morphology was evaluated by scanning and transmission electron microscopy, and atomic force microscopy, and the results point out that microwave heating exerts direct influence on the morphological characteristics of LNO films contributing towards the change in the grain size distribution, porosity and roughness. Conductivity was also investigated through four-probe measurements, which pointed out a conductive and ohmic behavior of the LNO thin films prepared via the polymeric precursor method where a direct relationship was found between the morphological characteristics and the electrical properties of LNO film.

Low-temperature short-time nitriding of Va-group metals, V, Nb and Ta, in uncracked NH3 gas under heating with concentrated solar power (CSP)

Over the last two decades, the authors have been using concentrated solar beam as the reaction heat source for synthesizing carbides and nitrides of d-group transition elements in view of usage of ecological renewable energy source in place of conventional heat sources using electricity or natural gas. In recent works, nitriding of VIa-group metals (Cr, Mo, W) and Fe in stream of NH3 gas with suppressed extent of dissociation (uncracked NH3) was attempted under heating with concentrated solar beam. It was demonstrated that mono-nitride δ-MoN of Mo and sub-nitride ɛ-Fe2N of Fe that are known to be impossible to synthesize in N2 gas environment even at elevated N2 gas partial pressure p(N2) up to 300bar were successfully synthesized by the reactions of these metals in stream of NH3 gas under heating with concentrated solar beam up to 800°C.In the present work, nitriding of Va-group metals (V, Nb and Ta) was attempted in stream of NH3 gas under irradiation of concentrated solar beam. After 90min heating in uncracked NH3 under concentrated solar beam up to 800°C, X-ray diffraction (XRD) characterization of the reaction products showed certain extent of nitriding progressed for all the specimens in spite of relatively low reaction temperature for short reaction duration.

Tuning the acid content of propylsulfonic acid-functionalized mesoporous benzene-silica by microwave-assisted synthesis

Propylsulfonic-acid functionalized mesoporous phenylene-silicas have potential use in catalysis and applications demanding protonic conduction such as fuel cells. Their synthesis by conventional co-condensation is time consuming and with poor control of the incorporation of sulfonic acid. Here we report a fast, microwave-assisted synthetic route to prepare these materials with controlled acid load and structural order. It is found that the microwave energy strongly improves the kinetics of the various steps of the process, including the self-assembly of precursors (stirring), consolidation of the framework (hydrothermal treatment), surfactant extraction and the oxidation of the thiol to the sulfonic acid group. The concentration of incorporated acid groups increases linearly with the self-assembly time under microwave radiation, enabling the largest improvement of all synthetic steps. However, the mesopore order decreases significantly for microwave-assisted self-assemblies in excess of 6 h, and for microwave-assisted hydrothermal treatments longer than 3 h. The multivariate analysis of kinetic data is presented and used to derive kinetic parameters enabling the prediction of the acid load and the structural order of the materials as a function of the synthesis time under microwave radiation. For similar acid contents, full microwave synthesis is completed within 12 h, whereas nearly 84 h are needed with conventional heating sources. The protonic conductivity increases linearly with increasing acid load regardless of the used combination of synthetic steps, including MW or not. This is seen as a confirmation that the distribution of the acid groups in the pore surface is not affected by MW.

Shaping metallic glasses by electromagnetic pulsing

With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals.

Effect of Temperature on the Wear Properties of Alloy Steel under Jatropha Curcas Biodiesel

This paper presents the effect of Jatropha curcas biodiesel on the wear properties of mild steel, which was coated by preplacement of TiC particulate and melting it using a conventional TIG torch arc heat source. The aim of the study is to investigate the wear behaviour of surface modified AISI 4340 steel and the uncoated AISI 4340 steel which were performed using CSM tribometer at four different temperatures viz., 100 °C, 120 °C, 140 °C, and 160 °C, with the presence of jatropha biodiesel. At the end of the tests, wear characteristics was investigated by weight loss measurements and changes of the exposed metal surface. Surface morphology was examined by scanning electron microscope and surface profilometry. EDX analysis was performed on the samples’ surface. Results showed that wear of alloy steel increases with increasing temperature. TiC coated alloy steel showed improved wear resistance as this alloy steel demonstrated lower wear volume loss as compared to the uncoated steel in presence of jatropha biodiesel at higher temperature.

Key issues and solutions in a district heating system using low-grade industrial waste heat

Industrial waste heat is increasingly being recognized as an important source of heat for DH (district heating) systems in cold regions to fill shortfalls in heating requirements, while consuming less fossil energy than with conventional heating sources. Most existing cases of industrial waste heat utilization for heating merely focus on heat recovery from a single waste heat source for heating either in the factory in which the heat is generated or other buildings in the vicinity. The purpose of this paper is to discuss the key issues related to a DH system using two or more kinds of low-grade industrial waste heat, at a temperature between 20 °C and 90 °C, for users a long distance away from the heat sources, including the collection and integration of multiple-grade waste heat sources, long-distance delivery of waste heat, and peak shaving of the system. Solutions to these three issues are proposed to increase the efficiency of the system and for further and better promotion of such a system: 1) “Tangency technology” is designed and applied to find the optimal method of collecting heat from multiple waste heat sources. 2) Lowering the temperature of the return water on the primary side has been proven to be crucial to the collection and long-distance delivery of industrial waste heat. 3) Systems integrating both industrial waste heat and fossil-fuel heat are depicted. Industrial waste heat always provides the base load for the DH system, while the fossil-fuel heat acts as the peak shaver. Lastly, a case study undertaken in Chifeng in northern China demonstrates how these solutions act in a first-ever DH demonstration project using multiple sources of waste heat from a copper smelter. In all, 390,000 GJ of waste heat was recovered, 35,000 t of CO2 emission was reduced, and over 150,000 t of water was saved.

Evaluation of an Organic Rankine Cycle Using a Non-Imaging Solar Concentrator for Different Working Fluids

The Organic Rankine Cycle (ORC) is a feasible technology that can be applied for small-scale power generation in residential and commercial buildings. However, a solar thermal power plant may not compete with that of a thermal power plant using conventional heat source such as coal or natural gas but environmental impact. On the other hand, the cost of a power plant may be reduced by improving the system performance. Using non-imaging concentrators can eliminate the necessity of sun tracking system. Covering the concentrators by evacuated glass tube can reduce the heat loss from the absorber, and improves the effective life-cycle of optical components. Therefore, a non-imaging concentrator was considered as a steam generator of solar power plant. In order to evaluate the system performance, simulations were conducted by using aspenHYSYS software for different working fluids. The maximum performance is obtained for the case of R-141b for the pressure difference of 39 bars to be 15.3%. The best performance improvement is attained for water and R-141b to be about 8.2% and 7.8%, respectively. The working fluid, R-141b shows a better performance due to its lower boiling point and may be preferable for small scale applications.

Evaluation of potential fossil fuel conservation by the renewable heat obligation in Korea

The developers of new buildings in South Korea are going to have a renewable heat obligation to meet some proportion of heating & cooling demand with renewable heat sources such as ground-source heat pumps, biomass wood pellet boilers and solar water heating panels from 2016. This study evaluated the potential fossil fuel conservation by implementation of the renewable heat obligation in Korea, based energy demand patterns of the target buildings and cost and performance of the renewable heat sources. Results show that most of the developers of new buildings will adopt a ground-source heat pump because of long lifespan and low variable cost under the current electricity tariff. Ground-source heat pumps consume electric power generated from fossil fuel as the major source for operation while solar and biomass do not. This implies that under the current plan the percentage of potential decrease of fossil fuel use will be much lower than the percentage of heating & cooling demand met by renewable heat sources. Reclassifying ground-source heat pumps as highly energy efficient conventional heat sources rather than renewable heat sources, as the International Energy Agency does, would correct this undesired outcome and is suggested as a policy correction.

Large accelerations from small thermal differences: case studies and conventional reproduction of microwave effects on palladium couplings

Many palladium-catalyzed coupling reactions been reported to proceed more quickly upon microwave irradiation than when they are warmed to the same temperatures by more conventional heat sources. The origins of this phenomenon in two Buchwald-Hartwig couplings have been investigated by collecting kinetic data, which show the differences arising from the two heat sources to be much less dramatic at early times than total reaction durations imply. The observed difference is attributed to the interplay of rapid catalyst deactivation with subtle variations between the early temperatures in microwave and conventional heating. Experimental elimination of these small thermal differences brought microwave and conventional heating results into close agreement in these and related reactions, adding to the growing consensus that in most systems, microwaves differ from traditional heating only by their thermal effects, rather than more exotic phenomena.

N-Butyl cyanoacrylate synthesis. A new quality step using microwaves.

Alkyl cyanoacrylates are interesting products for use in industry because of their properties enabling them to stick together a wide range of substrates. n-Butyl cyanoacrylate is one of the most successfully used tissue adhesives in the field of medicine because it exhibits bacteriostatic and haemostatic characteristics, in addition to its adhesive properties. At present, its synthesis is performed with good yields via Knoevenagel condensation using conventional sources of heating, but this requires a long processing time. The aim of this work was to look for a new way of synthesising n-butyl cyanoacrylate using microwave irradiation as the source of heating. This non-conventional source of heating most likely reduces the process time of the synthesis. In comparison with a conventional heating source, such as an oil bath, the results showed the advantages of this method whereby the n-butyl cyanoacrylate gave the same yield and quality with a reduction in the reaction time by a factor of 3-5-fold.

Ground Source Heat Pump and Conventional Heat Sources to Match the Design and Operation Mode for Energy Saving

According to China's current energy present situation, the use of renewable energy, saving energy and reducing consumption has become the energy industry development should follow the basic principles. Ground-source heat pump and conventional heat source composite system as a kind of building energy efficiency technology, mainly reflected in soil source heat pump renewable energy utilization aspects. In this paper the soil source heat pump and conventional heat source matching design and operation mode research, from the matching design principle chart, operation mode, the practical engineering application, economic and technical analysis into consideration, it is concluded that the soil source heat pump and conventional heat source composite system can be applied and research.

Industrial waste heat utilization for low temperature district heating

Large quantities of low grade waste heat are discharged into the environment, mostly via water evaporation, during industrial processes. Putting this industrial waste heat to productive use can reduce fossil fuel usage as well as CO2 emissions and water dissipation. The purpose of this paper is to propose a holistic approach to the integrated and efficient utilization of low-grade industrial waste heat. Recovering industrial waste heat for use in district heating (DH) can increase the efficiency of the industrial sector and the DH system, in a cost-efficient way defined by the index of investment vs. carbon reduction (ICR). Furthermore, low temperature DH network greatly benefits the recovery rate of industrial waste heat. Based on data analysis and in-situ investigations, this paper discusses the potential for the implementation of such an approach in northern China, where conventional heat sources for DH are insufficient. The universal design approach to industrial-waste-heat based DH is proposed. Through a demonstration project, this approach is introduced in detail. This study finds three advantages to this approach: (1) improvement of the thermal energy efficiency of industrial factories; (2) more cost-efficient than the traditional heating mode; and (3) CO2 and pollutant emission reduction as well as water conservation.