Tank Losses Research Articles

Slain Tiger: Confirming the Total Loss of a Fabled Tiger Tank at Prokhorovka

ABSTRACT The battle of Prokhorovka in July 1943 was undoubtedly a convincing Soviet victory, despite incurring heavy armored losses, the Red Army’s supremacy in artillery, anti-tank defense, armored reserves, and tenacity ensured that the German advance on Prokhorovka was halted. Despite this, Western historians have tended to fixate on the lesser armored losses suffered by the Germans; often without placing these losses in the wider context of the battle. This theme is continued further when Tiger tank losses at Prokhorovka are dismissed as myth or fable. This article will reveal the contrary is true and that in reality, the final myth of the battle of Prokhorovka is that no Tiger tank losses occurred. Using original German sources throughout the article provides irrefutable evidence that a German Tiger tank was destroyed on the Prokhorovka battlefield in July 1943.

Analysing and Computing the Impact of Geometric Asymmetric Coils on Transformer Stray Losses

Designing and manufacturing transformers often involves variations in heights and thicknesses of windings. However, such geometric asymmetry introduces a significant impact on the magnitude of stray transformer losses. This study examines the effects of asymmetric coils on the generation of stray losses within core clamps and transformer tank walls. A model has been introduced to ascertain the dispersion magnetic field’s value at a specific distance from the coil. The analysis extends to characterising the dispersion magnetic field reaching the tank walls by using electromagnetic simulation by a finite element method. It explores strategies to diminish stray losses, including the placement of magnetic shunts as protective shields for the tank walls. It delves into the efficacy of employing a transformer shell-type configuration to mitigate the magnetic dispersion field. The findings revealed that achieving greater symmetry in transformer coils can minimise stray losses. Specifically, the incorporation of magnetic shunts has the potential to reduce additional losses by 40%, while the adoption of a shell-type configuration alone can lead to a 14% reduction. This work provides valuable insights into optimising transformer designs, contributes a user-friendly tool for estimating additional tank losses, thereby enhancing the knowledge base for transformer manufacturers.

Performance analysis and optimization of a solar assisted heat pump-driven vacuum membrane distillation system for liquid desiccant regeneration

Liquid desiccant air-conditioning (LDAC) system is one of the excellent alternatives to conventional vapor compression refrigeration system due to its great energy-saving potential. However, regeneration of diluted liquid desiccant is the main energy-consuming process, and its performance plays a significant role in LDAC system. Recently vacuum membrane distillation (VMD) is becoming an emerging and promising separation process rely on the advantage of high permeate flux and low energy losses. The interest of usage solar energy techniques for feed solution heating in VMD systems is regarded as a sustainable path for membrane distillation process. In this work, a solar-driven VMD system incorporating a vapor-compression heat pump for liquid desiccant regeneration is introduced. An adapted solar/heat pump hybrid heating strategy has been devised to establish a connection between the heat-demanding process and the solar thermal supply. A comprehensive multicriteria assessment of energy, exergy, and environmental evaluation is conducted, and the influences of crucial parameters on both key components and system performance are evaluated to ensure a systematic examination. Results show that both the COP and STEC decrease obviously with the growth of the inlet solution temperature, whereas SEEC is improved abviously from 410.6 kW·h/m3 to 566.1 kW·h/m3 due to the effect of heat pump. The exergy analysis indicates that exergy losses in solar collector and stratified heat storage tank accounted for over 80 % of the total exergy losses. Additionally, single-objective optimization and multi-objective optimization are employed to explore the optimum operating conditions of key componets and whole system. Results show the ideal optimal solution can be obtained with a COP of 19.92 and a SEEC of 142.89 kW·h/m3 when the weights of COP and SEEC are taken as [0.5, 0.5].

Energy behaviour and economic analysis of a photovoltaic-thermal (PV/T) collector coupled with a reverse osmosis (RO) desalination unit in Tunisian climatic conditions: a feasibility study.

Water scarcity affects about onebillion people in the world. Around two billion people could be living in water-stressed areas by 2050. For this reason, the desalination is always evolving due to the importance of the water resources found in the seas and brackish water. As these systems are generally energy intensive, the use of a renewable energy source is among the most appropriate solution. In this paper, both experimental and numerical investigations have been conducted to evaluate the performances and the economic viability of aphotovoltaic-thermal collector intended to supply a reverse osmosis (RO) unit. Experimental study is based on the input-output and dynamic system testing (DST)according to ISO 9459-5 standard method and computations use the energy and mass balances of the PV/T collector and the RO plant. Results of DST testing showed that the loss coefficient of the PV/T, the tank loss coefficient and the total tank heat capacity are 10.46 W.m-2.K-1, 1.596 W.K-1 and 388MJ.K-1, respectively. The ability to couple the RO technology to PV/T systems has been demonstrated. The complete system has been simulated for a water salinity of 10,000ppm and climatic data of Borj-Cedria (Tunisia) site (longitude 10° 25' 41″ E and latitude 36° 43' 04″ N). Numerical investigations showed that the electricity needs of a small off-grid desalination unit could be met by using a 6.48m2 PV/T panel surface area. In this case, the purified water produced has a salinity of 1500ppm and the flow rate is 24,000l/day. For a grid connected site, the produced and auxiliary powers are found to be equal to 54% and 21%, respectively. Moreover, the economic cost of adding a PV/T system into an existing RO unit has been evaluated and the results showed that the payback period is 6years.

Modeling and Simulation of SWARA Path Loss Model for Underwater Acoustic Communication in Multipath Environment

Effective communication in underwater environments is essential for numerous applications, including marine research, oil and gas exploration, and underwater surveillance. However, signal loss during propagation is a significant challenge for underwater communication systems. Accurate mathematical models are necessary to develop and optimize communication systems for underwater environments. This research proposes a mathematical model, SWARA, that incorporates crucial parameters such as transmitter and receiver responses, channel conditions, node placements, and signal frequency to accurately model short-range losses in underwater medium. We conducted tank trials at the UWAA Lab, CARE, IIT Delhi to validate our simulation results, using a chirp signal with a frequency ranging from 25–35 kHz. Our simulation results show that the SWARA model effectively predicts short-range propagation losses in underwater media. Compared to experimental losses, the maximum and minimum simulated losses deviated by only − 0.18–0.10 W/Hz and − 0.36–0.19 W/Hz, respectively, indicating the accuracy of the model. Our tank trials further revealed the significant impact of projector and hydrophone placements on incurred losses, highlighting the importance of careful placement in the design of underwater communication systems. In conclusion, this research proposes the SWARA model for studying short-range losses in underwater tank, which effectively incorporates crucial parameters for accurate modeling. The model has practical applications in the design and optimization of underwater communication systems for short-range applications. This research provides important insights for the development of effective underwater communication systems.

Mathematical Modelling and Experimentation of Soy Wax 68℃ Encapsulated into Solar Tank (Case Study)

Governments worldwide are attempting to minimise CO2 emissions, and solar energy storage remains the most difficult problem to tackle in the current climate. Typically, domestic hot water is mainly used for heat process services in colder climates when the tank loss is significant. Any design modification can result in a higher solar yield. Since water is a perfect medium for heat storage, this article will examine different Solar Domestic Hot Water (SDHW) systems in cold climates such as Central Europe and hot and dry climates such as the Middle East (Syria). Linear modelling was conducted using R script software using coded values to define the optimal value using the response surface method (RSM). The programming phase uses the least-squares approach to provide a general rationale for the line's best-match position among the data points under consideration. For each variable, the coded values range from [-1, +1]. The number of experiments is determined by the formula 2k , where k is the variable number. Since each variable has two possible values [-1, +1], the total number of experiments was 23= 8. In addition to these experiments, we performed one more experiment for defining second-degree non-linear coefficients. The second-degree factors were checked to evaluate the non-linearity of the system. The experimental work was done in the laboratory; an insulated water tank filled with 5 litres of water was used. A capsulated PCM soy wax 68℃ test was conducted. For the charging phase, the response surface approach with non-linear correlation was used to determine the optimal number of samples and PCM quantity at two temperature levels. The results of temperature, sample numbers, and wax quantity demonstrate a 0.22, 2.3, and -1.12 first-degree magnitude effect, respectively. In addition, each two-factor interaction contour plot is depicted.

Optimization of collector area and storage volume in domestic solar water heating systems with on–off control—A thermal energy analysis based on a pre-specified system performance

Numerical simulations of solar water heating systems using on–off control were performed for four locations in the Portuguese territory, two collector types, and a wide range of parameters. Two main design parameters were considered: the collector area and the storage volume. An innovative technique was used to investigate the relationship between system performance and system parameters: a pre-specified annual solar fraction is selected and the optimal parameters needed to achieve this solar fraction are then computed. The optimum collector area is almost always higher for a double-glazed than for a single-glazed collector, suggesting that in Portugal, the single-glazed type is more effective for most solar water heating applications. This fact is more significant for lower solar fractions and warmer climates. A small increase in the optimum collector area leads to a very strong decrease in the optimum storage volume (an area increase of 1% leads to a volume decrease of 27%). Collector flow rate and storage volume increments result in lower collector areas. However, high flow rates lead to high pumping losses and lower collector efficiencies, and when the storage tank losses are significant, higher tank sizes may lead to higher collector areas. The solar fraction has a very strong impact on the collector area and storage volume (when the solar fraction increases from 0.5 to 0.99, the optimum collector area and storage volume increase about 17 and 56 times, respectively).

Cer Transformatörlerinde Elektriksel Parametrelerin Sonlu Elemanlar Yöntemi ile Analizi

Demiryolu sistemlerinde kullanılan elektrikli trenlerin hareket gücünü sağlamak için kullanılan motor sürücülerini cer transformatörleri beslemektedir. Cer transformatörleri lokomotiflerin altında veya üstünde, boyutları sınırlı bir alana yerleştirilmektedir. Bunun yanında tren sistemlerinde kullanılmakta olan ekipmanların güç ihtiyaçlarını karşılayabilmek için farklı gerilim seviyelerinde çok sayıda sargı yapıları cer transformatörlerinde bulunmaktadır. Demiryolu sistemlerinde sürdürülebilirlik, verim ve işletme güvenliğinin yüksek seviyede olması için cer transformatörlerinin tasarım parametrelerinin özel olarak incelenmesi gerekmektedir. Bu kapsamda tasarım aşamasında detaylı analizlerin gerçekleştirilmesi ve standartlar referans alınarak değerlendirilmesi önemli olmaktadır. Cer transformatörlerinde kısa devre empedansı, inrush akımları, kazan kayıpları, çekirdek kayıpları gibi kritik öneme sahip elektriksel parametrelerin doğru bir şekilde hesaplanması teorik yöntemler ile her zaman mümkün olmamakta veya çok zahmetli olmaktadır. Bu durumda sonlu elemanlar analizi yönteminin birçok açıdan avantajı bulunmaktadır. Sonlu elemanlar analizleri ile yüksek doğrulukta ve kısa sürede hesaplamalar yapılabilmektedir. Bu çalışmada örnek bir cer transformatörünün elektriksel parametreleri Ansys Electronics Suite sonlu elemanlar analizi yazılımı ile hesaplanmıştır. Hesaplanan parametreler ile ilgili olarak özet bilgiler verilmiş, analiz adımları açıklanmıştır. Bu kapsamda demiryolu sistemlerinde kullanılan trenlerin kritik elemanlarından biri olan cer transformatörlerinin elektriksel analizi için sonlu elemanlar yönteminin gerekliliği ifade edilmiştir.

Microbiome of Penaeus vannamei Larvae and Potential Biomarkers Associated With High and Low Survival in Shrimp Hatchery Tanks Affected by Acute Hepatopancreatic Necrosis Disease.

Acute hepatopancreatic necrosis disease (AHPND) is an emerging bacterial disease of cultured shrimp caused mainly by Vibrio parahaemolyticus, which harbors the lethal PirAB toxin genes. Although Penaeus vannamei (P. vannamei) postlarvae are susceptible to AHPND, the changes in the bacterial communities through the larval stages affected by the disease are unknown. We characterized, through high-throughput sequencing, the microbiome of P. vannamei larvae infected with AHPND-causing bacteria through the larval stages and compared the microbiome of larvae collected from high- and low-survival tanks. A total of 64 tanks from a commercial hatchery were sampled at mysis 3, postlarvae 4, postlarvae 7, and postlarvae 10 stages. PirAB toxin genes were detected by PCR and confirmed by histopathology analysis in 58 tanks. Seven from the 58 AHPND-positive tanks exhibited a survival rate higher than 60% at harvest, despite the AHPND affectation, being selected for further analysis, whereas 51 tanks exhibited survival rates lower than 60%. A random sample of 7 out of these 51 AHPND-positive tanks was also selected. Samples collected from the selected tanks were processed for the microbiome analysis. The V3–V4 hypervariable regions of the 16S ribosomal RNA (rRNA) gene of the samples collected from both the groups were sequenced. The Shannon diversity index was significantly lower at the low-survival tanks. The microbiomes were significantly different between high- and low-survival tanks at M3, PL4, PL7, but not at PL10. Differential abundance analysis determined that biomarkers associated with high and low survival in shrimp hatchery tanks affected with AHPND. The genera Bacillus, Vibrio, Yangia, Roseobacter, Tenacibaculum, Bdellovibrio, Mameliella, and Cognatishimia, among others, were enriched in the high-survival tanks. On the other hand, Gilvibacter, Marinibacterium, Spongiimonas, Catenococcus, and Sneathiella, among others, were enriched in the low-survival tanks. The results can be used to develop applications to prevent losses in shrimp hatchery tanks affected by AHPND.

Experimental and numerical investigation on head losses of a complex throttled surge tank for refined hydropower plant simulation

For a large hydropower plant (HPP) with long-distance tunnels, a surge tank needs to be installed to ensure the safety of the HPP during hydraulic transients (i.e., load changes in hydro-turbines). The head losses of the surge tank and its throttle are necessary conditions and evidence of the hydraulic design and one-dimensional (1D) simulation of the HPP. This study is conducted to investigate the head losses of a complex throttled surge tank for a refined 1D HPP simulation. Based on model experiments and computational fluid dynamics (CFD) simulations, the statistical laws of the total head loss coefficient are determined, and the dynamic refined formulas for the resistance and discharge coefficients are proposed. Finally, the proposed discharge coefficients are applied to refined 1D HPP simulations and compared with the traditional discharge coefficient. It is preliminarily revealed that the discharge coefficient undergoes a step change under load rejection and a continuous hump-shaped change under increasing loads. The water level results calculated using the proposed discharge coefficient differ by 1.69 m, i.e., 3.65% of the total height of the surge tank, compared with using the traditional discharge coefficient. This study can facilitate the understanding of hydraulic design and HPP optimization.

Reduction of evaporation losses in oil and oil derivatives storage tanks: A case study for warehouse in Pozega (Serbia)

One of the biggest problems related to mandatory tanks of oil and oil derivatives are evaporative losses in the tanks. It is well known that the storage, manipulation and transport of oil and oil derivatives results in the evaporation of the liquid. In the case of tanks where commodity reserves are stored for a long period of time, the most pronounced problems are "breathing" losses and degradation of the quality of petroleum products. Many of these volatile organic compounds also have a strong negative impact that is harmful to human health and the environment. The aim of this research is to improve system in order to reduce evaporative losses in the tanks which are used for mandatory reserves of oil and oil derivative in warehouse in location near Pozega in Serbia as well as to reduce the harmful impact on the environment with the proposed improvement measures.

Vehicle Emissions and Air Quality: The Early Years (1940s–1950s)

During the 1940s, an unusual form of air pollution was experienced in the Los Angeles (LA) area of Southern California. Referred to as LA smog, this pollution differed from previously known air pollution with respect to its temporal patterns (daytime formation and nighttime dissipation), eye irritation, high oxidant levels, and plant damage. Early laboratory and field experimentation discovered the photochemical origins of LA smog. Though mechanistic understanding was incomplete, it was determined that hydrocarbon (HC) compounds in the atmosphere participate in smog formation, enabling build-up of higher ozone concentrations than would otherwise occur. It being a significant source, there was great interest in characterizing and controlling HC emissions from motor vehicles. Considerable work was done in the 1940s and 1950s to understand how emissions varied with vehicle operating conditions and deterioration of engine components. During this time, procedures were developed (and improved) to sample and quantify vehicle emissions. Besides exhaust, HC emissions from crankcase blowby, carburetor evaporation, and fuel tank losses were measured and characterized. Initial versions of both catalytic and non-catalytic exhaust after-treatment systems were developed. The knowledge gained from this pre-1960 work laid the foundation for many advancements that reduced vehicle emissions and improved air quality during subsequent decades.

A reassessment of the tank battle between 4th Armoured Brigade and Panzerregiment 5 during Operation Crusader in North Africa on 19 November 1941

Operation Crusader took place in the wide context of an integrated, multi-servicetheatre-level offensive operation in the Western Desert and the Mediterranean fromOctober 1941 through to January 1942. Seen through this lens, Operation Crusader wassimply the Army and the Royal Air Force component of a multi-service theatre-leveloffensive conducted by Allied forces. The operation ended with an almost completedefeat of the Axis troops, the lifting of the seven-month siege of Tobruk and the retreatof the surviving Axis forces to a position on the border of the colonial provinces ofTripolitania and Cyrenaica, in central Libya.Operation Crusader was the first army-level offensive undertaken by the Alliedforces in World War II, lasting from 17 November 1941 to 15 January 1942.355 Theaim of Operation Crusader was to trigger a large-scale tank battle with Axis tank forcesoutside the besieged desert port of Tobruk in Libya, to destroy the Axis armouredforces, and to pave the way to lift the siege of Tobruk, which had been conducted bythe Axis forces since April 1941. Operation Crusader was the first step in a set of threeoperations expected to lead to the clearing of the North African coast from Axis forcesand subsequently allow an invasion of Sicily in 1942. The battle was the largest tankoffensive conducted by Allied forces in either World War I or World War II until theSecond Battle of El Alamein in late October 1942. It was characterised by a number oftank battles between the Axis forces under the command of General der PanzertruppenErwin Rommel and Allied infantry and armoured forces under Lieutenant-General AlanCunningham and then Lieutenant-General Neil Ritchie, who fought under the overalldirection of General Claude Auchinleck, the Commander-in-Chief Middle East. 356 357The conduct of the battle showed weaknesses in the doctrine of British armouredforces, but it ultimately ended in a victory for the Allied forces. This article analysesthe first clash of British and German tanks during Operation Crusader and provides anew perspective on the performance of an experienced British cruiser tank regiment,which calls into question the overall assessment of how British armour performedduring the battle. The re-assessment provided in this article is in particular related to theperformance of both sides in the battle and the performance of both sides against theirtactical objectives on the day, as well as the comparative losses in tanks. The article covers the first engagement of British 4th Armoured Brigade with Germanarmour during the opening stage of Operation Crusader between 17 and 20 Novemberin which it managed to thwart a German counterattack. Utilising primary documents,such as war diaries, messages and reports, this article provides a new perspective on theestablished view of the battle that also affects our view of the performance of Britisharmoured units at regimental level during this period of the Desert War. The articlepresents a reassessment of comparative tank combat performance in the early phaseof Operation Crusader by analysing the first engagement between Allied and Germanarmour with a view to correcting misconceptions that have until now clouded thehistorical record, such as the one expressed in General Auchinleck’s despatch on theperiod, “But our tanks and anti-tank guns were no match for the German, althoughthey were fought with great gallantry:”.358 It also considers hitherto unused primaryevidence to shed new light on the losses in tanks suffered by both sides during the battle,and considers how the opposing forces performed in the context of their operationalobjectives.

An exergy analysis for overall hidden losses of energy in solar water heater

This study investigates the hidden thermal losses of glass plate, collector plate, water pipe and storage tank of solar water heater in the process of energy conversion. The present non-conventional energy methods are insufficient, whereas the exergy analysis provides a remarkable solution. Thus, employing the exergy analysis, entropy generation, exergy destruction, and exergy efficiency of each subsystem of solar water heater are computed. The obtained results showed that the entropy generation and exergy destruction are high during the heat transfer in each subsystem. Henceforth, the existing solar water heater design is modified placing hexagonal honeycomb structure between the glass plate and the collector plate and also water pipe is insulated to trap huge amount of solar energy. The proposed design exhibits improved exergy efficiency when compared with the existing model, which enhances the performance of the system.

Estimation of Evaporation Losses of Bunker LNG

Analysis of efficiency of transport systems using liquefied natural gas (LNG) as fuel is impossible without a comprehensive understanding of the volumes of fuel LNG losses from evaporation during main technological operations: transportation (storage), bunkering, and cool-down of fuel tanks. Despite active development of water and land natural gas vehicles, practical approaches for obtaining appropriate estimates in a wide range of characteristics of cargo tanks have not been previously published.The objective of this work is to analyze LNG losses in road, rail and ship tanks (with a capacity of up to 5600 m3), as well as in tank containers, provided that LNG is stored with an overpressure of about 5–7 atmospheres.In the work, numerical modelling was used as a method. The evaporation process of LNG is described using models of heat exchange between the liquid phase of LNG, its vapours, as well as a cargo tank and the external environment. This makes it possible to simulate the behaviour and phase transformations of LNG during its storage in a tank, as well as during main technological operations. Numerical modelling of thermodynamic processes during storage of LNG is performed using a computer simulation model implemented in AnyLogic environment. Quantitative estimates of LNG losses during bunkering and cool-down of fuel tanks were obtained based on analytical calculations.An analysis of sensitivity of the created models to various parameters, as well as massive numerical calculations, made it possible to construct regression relationships to determine LNG losses during operations under consideration. The obtained dependencies can be used to search for the most effective configurations of the system for low-tonnage LNG transportation, as well as to perform economic assessments of feasibility of using LNG as fuel for water and land transport.

A self-sustainable solar desalination system using direct spray technology

Solar desalination offers a sustainable solution to growing global water demand due to the geographical coincidence between high solar availability and severe water scarcity. This paper presents a self-sustainable solar desalination system combining a spray-assisted low-temperature desalination system, solar thermal collectors, and heat storage tanks. A mathematical model is firstly developed and validated with laboratory pilot for the proposed large-scale solar-powered desalination system. Afterward, the long-term productivity and energy efficiency of the system is evaluated under the climatic conditions of Makkah, Saudi Arabia. The proposed solar desalination system is able to provide an uninterrupted water supply of 20 kg/day for per square meter solar collector area, and the value can be further increased by optimizing the interactions of the three subsystems, i.e. efficiency of the solar collectors, temperature and heat losses in the storage tank, and energy efficiency of the desalination system. With a collector area of 360 m2, the annual productivity is maximized when the feed flowrate is 1.7 kg/s and the diameter of the heat storage tank is 1.9 m. The desalination cost is estimated to be $1.29/m3, which is much lower than other solar thermal desalination systems.

Computation of Stray Losses in Transformer Bushing Regions Considering Harmonics in the Load Current

The presence of harmonics in the load current considerably increases stray losses in electric transformers. In this research paper, a new model for computing the electromagnetic field (EMF) and eddy current (EC) losses in transformer tank covers is derived considering harmonics. Maxwell’s equations are solved with their corresponding boundary conditions. The differential equation thus obtained is solved using the method of separation of variables. The obtained expressions do not require the use of special functions, accommodating them for practical implementation in the industry. The obtained formulas are evaluated for different spectrum contents of the load current and losses. The results are in good agreement with simulations carried out using the Altair Flux finite element (FE) software.

Loss analysis of gravitation vortex type water turbine and influence of flow rate on the turbine’s performance

A gravitation vortex type water turbine is a water turbine that uses gravitational vortices generated upon water draining from a tank bottom and can generate power at low head and low flow rate. In our case, given its operation in a free surface flow field, it is critical to quantitatively understand the performance and hydraulic loss at various flow rates for its design and operation. Accordingly, we investigated the influence of flow rates on the performance of the gravitation vortex type water turbine by conducting experiments and free surface flow analysis. Using the analysis results, we proposed a loss analysis method and quantitatively evaluated the hydraulic loss. We found that the effective head and the turbine efficiency increased as the flow rate increased; hence, the turbine output increased at a rate greater than the increase rate of the flow rate. Our study revealed that among the losses that occurred in the water turbine, the tank loss and tank outlet loss were the most dominant, followed by the friction loss inside the tank, whereas the runner loss and friction loss in the runner were small.

Energy modeling of solar water heating systems with on-off control and thermally stratified storage using a fast computation algorithm

This work presents a simplified model for the rapid computation of the yearly solar fraction of direct solar water heating systems using on-off control. Thermal stratification was included using a simple one-dimensional multi-node model. A time-step dependency analysis showed that a time step of 0.05h is a good compromise between accuracy and computation speed. The solar fraction increases with collector flow rate when the flow rate is low. In fully-mixed storage, the solar fraction keeps increasing with flow rate, although with a decreasing rate of increase. However, in stratified storage, the solar fraction reaches a maximum at an optimum flow rate, before it starts decreasing with flow rate. When the number of tank nodes increases from 1 to 4, the maximum solar fraction increases 5–28%; this increase is superior for less efficient collectors and lower collector areas. In low-stratified systems, the optimum flow rate is the maximum allowed by the system. However, in stratified systems, the optimum flow rate is reduced to values of 0.006–0.016m3h−1 per square meter of collector area. Unless the tank walls are covered by a rather thick layer of thermal insulation (about 0.2m), storage tank losses cannot be ignored.

A Case Study of Greenhouse-Gas-Emissions Measurements and Reduction-Potential Evaluation During Oil and Gas Production in China

Summary Reducing greenhouse–gas (GHG) emissions in oil and gas production could provide several benefits, including energy conservation, cost reduction, and economic returns. The direct–emissions measurements and reduction–potential evaluation are the prerequisites to achieve an effective reduction goal in GHG emissions. On the basis of the survey of production processes and related parameters, we identified and measured a series of GHG–emissions sources. The emissions sources were measured, including production processes and leakage–prone facilities such as dehydrators, boilers, heaters, associated gas–treatment plants, light–hydrocarbon–recovery units, storage tanks, and gas flaring. A series of leakage–detection/measurement instruments was applied as well, such as flow samplers, impeller flowmeter, gas detectors, and gas–flow probes. On the basis of the measured emissions data, we then used a simulation model to evaluate the specific forms, sources, and reduction potentials of the GHGs. The measured GHG emissions showed that evaporation and flashing losses from storage tanks were the largest source, accounting for 86% of the total methane (CH4) emissions and 42% of the total GHG emissions. The contribution of CH4 emissions from heaters and boilers during incomplete combustions was less than 1% of the total CH4 emissions and approximately 16% of the total GHG emissions. When controlling technology on storage–tank losses was applied, CH4 emissions could be reduced by 81.7% and the GHG emissions could be reduced by 39.9%. Furthermore, such controlling technologies also presented substantial economic benefits through the recovery of fuel gas. In this study, the recovery potentials of various GHG–emissions sources were analyzed. In addition, a preliminary cost/benefit analysis was performed per the emissions categories, reduction potentials, and the feasibility of reduction technologies. Finally, the probability of the application of such reduction technologies was evaluated.