Journal of Energy Engineering

The relationship between air pollution and energy consumption is a hot topic that is receiving increased attention by industry, regulatory agencies, as well as the public. China is currently undergoing a profound economic and social transition. Since the late 1990s, China’s energy production and consumption have undergone an unexpectedly precipitous up-and-down fluctuation, and the related air pollution has changed dramatically. In this study, energy use and the related air pollution during the past years are analyzed and discussed in detail. Further, suggestions on sustainable energy use, air pollution control, as well as $\mathrm{C}{\mathrm{O}}_2$ abatement are proposed. By 2003, the total primary energy consumption of China had reached $1678.00\text{million}\mathrm{tons}$ (MT) of standard coal equivalent. As a result, emissions of $\mathrm{S}{\mathrm{O}}_2$ and $\mathrm{N}{\mathrm{O}}_X$ increased to 21.58 and $16.13\mathrm{MT}$ in 2003, respectively. Acid rain pollution worsened nationwide after 2000, with the areas of acid rain remaining stable while some seriously acid rain polluted areas worsened. This implies that more rigorous regulations, standards, and effective economic policies are needed.

A high-performance solar collector suitable for a solar-assisted drying system was designed, fabricated, and tested. Solar-assisted drying systems consist of the solar collector array, auxiliary heater, drying chamber, and the air distribution systems. The solar collector was a double-pass solar collector and has upper and lower channels. The lower channel of the solar collector was filled up with porous media, which also acts as a storage medium. The outlet temperature and the performance of the system increased with the presence of the porous media. The collector width and length are 120 and $240\mathrm{cm}$ , respectively. The upper channel depth is $3.5\mathrm{cm}$ and the lower channel depth is $10.5\mathrm{cm}$ . The solar collector array consists of six solar collectors, arranged as two banks of three collectors in series. The collectors were joined in series using internal manifolding. A temperature of $90°\mathrm{C}$ can be reached at a solar radiation level of $800\mathrm{W}∕{\mathrm{m}}^2$ , ambient temperature of $30°\mathrm{C}$ , and mass flow rate of $0.06\mathrm{kg}∕\mathrm{s}$ . The solar-assisted drying system was used for drying of oil palm fronds from moisture content of about 63% to moisture content of about 15%, for a drying time of about $7\mathrm{h}$ . The overall system efficiency is about 25%.

Petroleum-based transformer oil performs the dual roles of insulator and electrolyte depending on charges in the oil. The availability of charges for conduction influences the level of voltage breakdown in the mineral oil and depends on the intensity of physicochemical processes such as redox action, hydrolysis, photodegradation, sludge/particle development, and gas formation arising from thermal, mechanical, chemical, and electrical stresses in the oil. Previous investigators have focused mostly on single oil aging indicators to build models for estimation of the aging rates of transformer oils, within a time frame that is too short relative to the operational service life of transformers. In this research, the interdependence of oil voltage breakdown and changes in oil physicochemical characteristics was investigated experimentally using T24 and T14 oils. Tests were performed with a DTS-100D oil tester for voltage breakdown and a HKV 4000 series high kinematic viscosity bath. The calculated activation energies are $26.2{\mathrm{KJm}}^{-3}$ for T24 and $25.4{\mathrm{KJm}}^{-3}$ for T24 transformer oils, respectively. Neglecting catastrophic failure from environmental hazards, the estimated service lives of T14 and T24 transformers that are herein analyzed are 40 and 43 years, respectively. Their degradation constants were experimentally determined to be $7.38\times {10}^{-12}$ and $6.98\times {10}^{-12}{\mathrm{L}}^{-1}{\mathrm{S}}^{-1}$ , respectively.

Theoretical and experimental investigations on an unglazed solar hot water heater with integrated storage system were conducted. The system was comprised of a collector and storage tank which was integrated into one unit. All parts of the system have been fabricated from fiberglass reinforced polyester (GFRP). The absorber plate has water tubes of semielliptical shape. The width and length of the absorber plate were 1.4 and $1.8\mathrm{m}$ , respectively. The absorber plate was fabricated from GFPR using a special resin composition that provides good thermal conductivity and absorptivity. The storage tank has a capacity of $496\mathrm{L}$ . The storage tank is of sandwich construction with a core material made of polyurethane foam that combines stiffness and lightness of the structure with very good thermal insulation properties. An average tank temperature of $53°\mathrm{C}$ was achieved at an average solar radiation level of $700\mathrm{W}∕{\mathrm{m}}^2$ and ambient temperature of $28°\mathrm{C}$ . The thermal efficiencies of the system were evaluated at 48 and 57% for cloudy and clear days, respectively. Transient performance of the system was predicted by solving the mathematical models consisting of energy balance equations of the system that have been converted to finite difference form and solved by a personal computer. The experimental results were in close agreement as has been found with the theoretical predictions.

Geothermal heat pumps can be considered a sustainable technology, as they reclaim and recycle thermal energy from the earth. In climates with a near balance in the annual heating and cooling loads, they function essentially as a seasonal energy storage scheme. This paper presents an overview of the technology. The various types of geothermal heat pumps are explained along with their relative merits. Detailed discussion is included on the most common method of ground coupling for commercial scale applications, the vertical borehole heat exchanger. Issues with sizing the heat exchanger and grouting it are discussed, as well as the motivation for in situ thermal properties testing. In-building equipment, including the heat pumps themselves, is briefly described. Experience with geothermal heat pumps to date is presented for both residential and commercial scale applications. Regional market penetration and competitiveness are also discussed for both residential and commercial scale applications. The paper concludes that the overall outlook for expanded application of geothermal heat pumps is very favorable.

The Environmental Effects Committee of the ASCE Energy Engineering Division has been developing a report on “Energy Production and Reservoir Water Quality” for publication. The report covers the regulatory framework that dictates much of the procedures for studies related to this topic, the fundamental reservoir hydrodynamics and water quality modeling used in preparing studies, the kinds of studies that can be prepared at different levels of analysis, and a series of applications that illustrate the problems encountered and applications of the various techniques. This study of hydrothermal modeling as applied to examining cooling tower alternatives for an existing steam electric station on a moderately large reservoir is included in this report and is presented here as an illustration of the types of studies included. This particular study subtended the usual steam electric plant cooling water discharge studies that relate to specific regulatory thermal plume size standards, and had to be designed around developing plant and cooling tower operations that would meet specific fisheries requirements for a zone of passage and refuge for fishes throughout the receiving embayment. After being used in developing cooling tower and plant operating details for the designers to work with, it was required that the hydrothermal modeling results be verified under actual tower operating conditions. In addition, it was required that the impact of the combined operations on dissolved oxygen be examined in detail. This paper covers the background to setting up the study, the kinds of statistical comparisons used to verify the hydrothermal studies, and similar studies for the analysis of dissolved oxygen distributions.

Wind energy conversion systems appear as an attractive alternative for electricity generation. To maximize the use of wind generated electricity when connected to the electric grid, it is important to estimate and predict power produced by wind farms. The power generated by electric wind turbines changes rapidly because of the continuous fluctuation of wind speed and wind direction. Wind power can be affected by many other factors such as terrain, air density, vertical wind profile, time of a day, and seasons of a year and usually fluctuates rapidly, imposing considerable difficulties on the management of combined electric power systems. It is important for the power industry to have the capability to perform this prediction for diagnostic purposes—lower than expected wind power may be an early indicator of a need for maintenance. A multilayer perceptron (MLP) network can be used to estimate wind turbine power generation. It is usually important to train a neural network with multiple influence factors and big training data set. The extended Kalman filter training algorithm has to be parallelized so that it can provide fast training even for large training data sets. The MLP network can then be trained with the consideration of various possible factors, which can cause influence on turbine power production.

The present work deals with evaluating the energy end exergy efficiency of box-type (SBC) and parabolic-type solar cookers (SPC). Energy and exergy analyses were applied to solar cookers (SCs). Thermodynamic considerations required to develop rational and meaningful methodologies for the evaluation and comparison of the efficiency of the SCs were defined. It was found that the average daily water temperature from 10:00 to 14:00 solar time was 344.4 and $333\mathrm{K}$ in the SBC and SPC, respectively. The average daily temperature difference in the SBC and SPC was 42.97 and $31.56\mathrm{K}$ , respectively. The results of this study show that the difference between the results of energy and exergy analyses is significant. The energy output of the SBC ranged from $8.2\text{to}60.2\mathrm{W}$ , whereas it was varied between 20.9 and $73.5\mathrm{W}$ for the SPC for the same time interval. The exergy output for the SBC ranged from $1.4\text{to}6.1\mathrm{W}$ , whereas it was in the range $2.9–6.6\mathrm{W}$ for the SPC. A linear and polynomial regression of the plotted points was used to find the relationships between energy/exergy outputs, and efficiencies and temperature difference. The energy and exergy outputs at a temperature difference of $50\mathrm{K}$ for the SBC and SPC were estimated to be 26.5 and $124.5\mathrm{W}$ and 5.23 and $12.02\mathrm{W}$ , respectively. The energy and exergy efficiency for the SBC and SPC was in the range 3.05–35.2%, 0.58–3.52% and 2.79–15.65%, 0.4–1.25% during the experimental period.

Turkey has a large economy and, thus, it expects a very large growth in energy demand. Today, Turkey’s economy is mainly dependent on oil, natural gas, and electricity. On the other hand, Turkey’s energy production meets nearly 35% of its total primary energy consumption. Turkey is an energy importing country. Turkey presently has considerable renewable energy sources. The most important renewable sources are hydropower, wind, solar, geothermal, and biomass. Turkey has about 1% of the total world hydroelectric potential and its significant potential for geothermal power production is ranked seventh in the world. This paper presents the energy situation and potential of the renewable energy sources in Turkey.