Collector Inlet Research Articles

Investigation of possible sources of water-soluble organic carbon particles observed with an online monitoring system

Abstract In this study, an instrument for the continuous measurements of water-soluble organic carbon (WSOC) component in fine particulate matter was developed and its field measurement results were presented. The instrument for collecting atmospheric aerosol particles for the online WSOC analysis uses an aerosol growth technology. Briefly, ambient particles, with aerodynamic diameters less than 2.5 μm, are collected via a cyclone inlet collector by rapidly mixing saturated water vapor with the ambient aerosol. The resulting supersaturated water vapor condenses on all the particles. The resulting liquid is separated from the air stream by an air–liquid separator, filtered, and the carbon content quantified using a total organic carbon analyzer, providing a continuous 4-min integral measurement. An evaluation of the accuracy of the online WSOC measurement system was performed by comparing the results with 24-h filter-based measurement data. The relationship between the 24-h averages of the 4-min data and the 24-h integrated data of the WSOC measurements indicated that the online WSOC concentration was 16% lower than that of the filter-based measurement. The online measurements of WSOC in fine particles were performed in September 2009 at a photochemical network near an industrial complex. Conditional probability functions were used to identify likely local emission source locations of the WSOC observed at the site, indicating that the major WSOC contribution to the site came mostly from the southeasterly (120−150°) and southwesterly (165–210°) directions, which brought air from a coal-fired power plant and traffic on the roads. Based on the temporal evolutions of SO2 and WSOC concentrations, wind direction with respect to the station angle of individual sources, wind speed, and source distance, it was shown that the presence of concurrent transients in SO2 and WSOC concentrations observed for a specific period is likely due to the influence of coal-fired power plants.

Experimental investigation and optimisation study of a direct thermosyphon heat-pipe evacuated tube solar water heater subjected to a northern maritime climate

SYNOPSIS A proprietary heat-pipe Evacuated Tube Solar Water Heater (ETSWH) originally designed for collection of solar energy using forced fluid circulation was operated using thermosyphon fluid circulation. The thermal performance of this solar water heating system was monitored from October 2006 to June 2007. The ETSWH array was inclined with the expected collector outlet at a higher datum level than the expected collector inlet to provide a hydrostatic pressure differential across the manifold. During the monitoring period it was observed that thermosyphon flow was not always in the expected direction, with flow reversal occurring when the collector inlet temperature was greater than that of the outlet. When the evacuated tube solar water heater manifold was inclined at 1° to the horizontal, reverse fluid flow was observed to occur for 69% of the monitored diurnal periods. Diurnal reverse circulation lowers system efficiency by reducing thermal stratification in the hot water storage tank via convective entrainment and mixing. The thermal performance of the ETSWH was monitored continuously from January 2007 to June 2007 with the manifold inclined at 5° to the horizontal. Over this time period it was found that fluid flow reversal arose for 22% of the diurnal periods considered, resulting in a 47% improvement in diurnal storage efficiency compared to when the system had its manifold inclined at 1°. The long term diurnal storage efficiency of the optimised system inclined at 5” was measured as 66%.

Constructal solar chimney configuration

In this study, we describe the constructal-theory search for the geometry of a solar chimney. The objective is to increase the power production over the area occupied by the plant. The ratio height/radius, maximum mass flow rate and maximum power under the constraints of a fixed area and volume are determined. We find that the power generated per unit of land area is proportional to the length scale of the power plant. The analysis is validated by a detailed mathematical model. Pressure losses are reported in terms of the dimensionless length scale of the system, and are illustrated graphically. They indicate that the pressure drop at the collector inlet and at the transition section between the collector and chimney are negligible, and the friction loss in the collector can be neglected when the svelteness (Sv) of the entire flow architecture is greater than approximately 6.

Experimental and numerical investigation on thermal and electrical performance of a building integrated photovoltaic–thermal collector system

An experimentally validated computational fluid dynamics (CFD) model of a novel building integrated photovoltaic–thermal (BIPV/T) collector is studied to determine the effect of active heat recovery on cell efficiency and to determine the effectiveness of the device as a solar hot water heater. Parametric analysis indicates that cell efficiency can be raised by 5.3% and that water temperatures suitable for domestic hot water use are possible. Thermal and combined (thermal plus electrical) efficiencies reach 19% and 34.9%, respectively. A new correlation is developed relating electrical efficiency to collector inlet water temperature, ambient air temperature and insolation that allows cell efficiency to be calculated directly.

Buoyancy Effects on Thermal Behavior of a Flat-Plate Solar Collector

Theoretical and experimental investigations of the flow and temperature distribution in a 12.53m2 solar collector panel with an absorber consisting of two vertical manifolds interconnected by 16 parallel horizontal fins have been carried out. The investigations are focused on overheating and boiling problems in the collector panel. Single-phase liquid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics (CFD) calculations. Differently designed collectors are investigated with different collector fluid volume flow rates. The effect of friction and the influence of the buoyancy effects are considered in the investigations. Further, experimental investigations of the solar collector panel are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the back of the absorber tubes. The measured temperatures are compared to the temperatures determined by the CFD model and there is a good agreement between the measured and calculated temperatures. Calculations with the CFD model elucidate the flow and temperature distribution in the collector. The influences of collector fluid flow rate and inlet temperature on the flow and temperature distribution are shown. The flow distribution through the absorber tubes is uniform if a high flow rate of 10.0l∕min is used. By decreased collector fluid flow rate and by increased collector fluid inlet temperature, the flow distribution gets less uniform due to the influence of buoyancy force. If the collector fluid flow rate is small and the collector fluid inlet temperature is high enough, severe nonuniform flow distribution may happen with a small flow rate or even zero or reverse flow in the upper horizontal strips, resulting in overheating or boiling problems in the strips. The CFD calculations elucidate the flow and temperature distribution in the collector panels of different designs. Based on the investigations, recommendations are given in order to avoid overheating or boiling problems in the solar collector panel.

Temperature field of solar collector and application potential of solar chimney power systems in China

AbstractA study on the temperature field of a solar collector in China's first pilot solar chimney thermal power setup was carried out, which is important to the evaluation of the performance of solar chimney power system. It was found that the air temperatures in the south were a little greater than those in the north, and that the temperature rise of collector inlet ambient air reached 24 and 12°C on a typical warm day and a typical cool day respectively. Also, the potential application of solar chimney power systems in China was estimated. The results showed the potential electric power reached 2·73 × 1020 J, also lessening the emission of CO2 by 1·41 × 1023 to 4·41 × 1023 tons compared to the coal fire stations with the same capacity.

Bench assembly for diesel engine tests with water injection in an inlet collector

The paper describes the assembly of the motor bench for toxicity, profitability and capacity tests of diesel engine. The authors estimate the thermal balance at water injection in an inlet collector. Recommendations for the choice of devices for measurement of these parameters are given.

Flow distribution in a solar collector panel with horizontally inclined absorber strips

The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontally inclined strips. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics (CFD) calculations. Further, experimental investigations of a 12.5 m 2 solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured temperatures are compared to the temperatures determined by the CFD model and there is a good similarity between the measured and calculated results. Calculations with the CFD model elucidate the flow and temperature distribution in the collector. The influences of different operating conditions such as flow rate, properties of solar collector fluid, solar collector fluid inlet temperature and collector tilt angle are shown. The flow distribution through the absorber fins is uniform if high flow rates are used. By decreased flow rate and decreased content of glycol in the glycol/water mixture used as solar collector fluid, and by increased collector tilt and inlet temperature, the flow distribution gets worse resulting in an increased risk of boiling in the upper part of the collector panel.

On the calculation of solar utilizability for south oriented flat plate collectors tilted to an angle equal to the local latitude

The utilizability or ϕ-curve method is a design method for some types of solar energy systems that use flat-plate solar collectors. It can be a very useful design tool, for the preliminary design or the design of small systems, cases where methods easy to use and apply are required. In this paper, a simple method to calculate monthly average hourly and daily flat plate collector utilizability is presented. It is based on empirical correlation of ϕ with independent variables that separate meteorological and collector parameters, making possible quick evaluations of changes in collector design and collector inlet temperature. In general, the method reduces the calculations required to determine ϕ, and gives good results compared to long-term hourly simulations as well as to existing hourly and daily utilizability calculations methods.

Flow Through a Solar Chimney Power Plant Collector-to-Chimney Transition Section

A solar chimney power plant consists of a large greenhouse-type collector surrounding a tall chimney. The air, heated within the collector, passes through an inlet guide vane (IGV)cascade and then through a transition section to a turbine that powers a generator. The transition section contains the turbine inlet guide vanes that support the whole chimney and guides the flow entering the turbine. The primary objective of the study was to determine the loss coefficient and mean exit swirl angle of the flow passing through the collector-to-chimney transition section of a full-scale solar chimney power plant as dependent on IGV stagger angle and collector roof height. Very good agreement was found between experimental values measured in a scaled model and commercial CFD code predictions of flow angles, velocity components, and internal and wall static pressures. The agreement between measured and predicted total pressure loss coefficient was reasonable when considering how small it is. The CFD code served to extend the predictions to a proposed full-scale geometry. Semi-empirical equations were developed to predict the loss coefficient and turbine mean inlet flow angles of solar chimney power plants as dependent on collector deck height and inlet guide vane setting angle. The two empirical equations may be useful in solar chimney plant optimization studies.

Solar Chimney Power Plant Performance

This paper evaluates the performance of a large-scale solar chimney power plant. The study considers the performance of a particular reference plant under specified meteorological conditions at a reference location in South Africa. A computer simulation program is employed to solve the governing conservation and draught equations simultaneously. Newly developed convective heat transfer and momentum equations are included in the numerical model and multiple simulations are performed. Results indicate 24hr plant power production, while illustrating considerable daily and seasonal power output variations. It is shown that plant power production is a function of the collector roof shape and inlet height.

Development of a dust collector inlet hood for enhanced surface mine drill dust capture

Surface mine drill operators have the highest frequency of overexposure to quartz dust, and drilling is one of the occupations associated with the highest incidence of silicosis. Previous field assessment studies of drilling machines indicate that they can emit some of the highest airborne respirable quartz dust concentrations found at surface mining operations. Typically, the surface mine drills are equipped with dry dust collector systems to capture the dust being flushed with compressed air from the hole during the drilling process. The overall control effectiveness of the dust collector system is initially dependent on capturing the dust cloud at the source via the collector inlet. To assist the initial capture of the dust being flushed from the drill hole, the bottom of the drill deck is typically shrouded or enclosed on all sides to help contain the dust for the collector inlet plenum located on the underside perimeter of the drill deck. Openings, gaps and breaches in the shroud enclosure permit dust to escape dust collector capture. 1 Mention of any company name or product does not constitute endorsement by the National Institute for Occupational Safety and Health. The National Institute for Occupational Safety and Health (NIOSH) has developed a collector inlet hood that reconfigures the inlet plenum around the drill steel and above the hole to enhance dust capture. Laboratory development and testing show that this inlet hood improves dust capture by an average of nearly 50% over a wide range of collector flows and shroud leakage areas. This report describes the laboratory and subsequent field testing of this inlet hood concept.

배기매니폴드 직접부착 촉매장치의 배기 유동특성

The exhaust gas flow in the inlet collector of close coupled catalyst(CCC) adapted to the exhaust manifold is very complex flow because the exhaust gas is a pulsation flow with several port flow. The distribution of gas flow and temperature in inlet collector effect to the efficiency of catalytic converter. In this study, it measures temperatures on several point in inlet collector with two kind of inlet collector volume. And it analyzes with CFD to exhaust manifold and close coupled catalyst for temperature and flow. Comparing to measured and analyzed result, it find increasing of collector volume effects to catalyst temperature distribution and uniformity of catalytic converter<br/>

Experimental investigation of temperature and flow distribution in a thermosyphon solar water heating system

Natural circulation solar water heating systems are available in varying collector geometries (and materials), storage tank capacities and specifications of individual components. Though theoretical and experimental studies including the test procedures are available to estimate the performances of these systems, detailed experimental studies showing the temperature profiles of the absorber plate, water temperature in the riser and water flow in the riser are few. This paper presents details of experimental observations of temperature and flow distribution in a natural circulation solar water heating system and its comparison with the theoretical models. The measured profile of the absorber temperature near the riser tubes (near the bottom and top headers) conforms well with the theoretical models. The values at the riser tubes near the collector inlet are found to be generally much higher than those at the other risers on a clear day, while on cloudy days, these temperatures are uniform. The mean absorber plate and mean fluid temperature during a day has been estimated and compared with theoretical models. The temperature of water near the riser outlets was found to be fairly uniform especially in cloudy and partly cloudy days at a given plane during a day. The temperature of water in the riser depends on its flow rate. Measurements of glass temperature were also carried out.

GJ-CHART: A SIMPLE DESIGN METHOD FOR PARTIAL SOLAR HEATED POLYVALENT MODULAR DRYERS WITH HEAT EXCHANGER

A supplement to the «GJ-CHART» method is presented in this article. It concerns a polyvalent modular drying system with a heat exchanger. Two configurations were studied: in the first, an exchanger is placed at the inlet of the conventional heat source and in the second, the exchanger is placed between the dryer outlet and collector inlet. This method was also developed for drying 27 kg of apple slices in single layers on the trays of the modular dryer. This design method can be generalized to provide a mean for quick estimation of the long-term performance of the partially solar heated polyvalent modular drying system

Computer simulation of the performance of a thermosyphon solar water-heater

The instantaneous collector-efficiency has been determined as a function of the time of day and correlated with the thermosyphonic-flow rate of water and the temperature difference between the water at the collector's inlet and outlet. The model was also used to predict the monthly and yearly solar-contribution of the system for two different load profiles. The results of the simulation indicate that the yearly solar contribution of the system for a low-consumption profile is about 89% as compared with 63% for a high consumption pattern.

Exergy optimization of flow rates in flat-plate solar collectors

The optimal flat-plate collector mass flow rate is determined by maximizing the exergy (available energy) delivery of the collector as the objective function. Collector and storage dynamics are neglected. Although the case where the pumping power loss is ignored results in bang-bang control, the case where this loss is included in the exergy equation results, after some assumptions, in an optimal mass flow rate that is a function of collector parameters, inlet and ambient temperatures and solar heat gain. Daily performance of a typical flat-plate solar collector with optimum mass flow rate is compared with the performance of the same collector using the mass flow rate obtained by maximizing the difference between the collected thermal energy and the required pumping power.

Improvement in solar air collector performance with vaned diffuser

Modifications made in a solar air collector inlet duct to achieve uniform velocity of air in the absorber duct are described. Measurements of temperature and pressure at various points in the duct gave information on the distribution of air in the absorber duct. A thermal performance test conducted on the collector with a vaned diffuser showed some significant improvement compared with a diffuser without vanes.

The approximate temperatures within a flat-plate solar collector under transient conditions

Some of the heat resistances of a conventional flat-plate solar collector are smaller than others. Using this property, analytic approximations of the temperatures within the collector at a moment t = 0, are derived. They are expressed as functions of the time-varying behaviour of the insolation, the ambient temperature and the fluid outlet and inlet temperature. In particular, the fast-varying temperature of the fluid near the collector inlet has been shown. Some applications are mentioned, in which coarser approximations of the temperatures are possible. A simple, one-capacity differential equation describes the fluid temperature, in that case.

An analysis of solar heating systems that use vapor-compression cycles

This paper analyzes the technical and economic performance of solar heating systems that use vapor-compression cycles, circulating a compressible fluid as the working fluid. With conventional solar heating systems that use water or as their working fluid, the collector inlet temperature is equal to that of the storage outlet temperature. Operating the system on a cold day can result in large thermal losses to the surroundings and, thus, low useful heat gains. A vapor-compression cycle may be attractive because it allows the collector inlet temperature to be lowered so that the heat gain of the collector can be increased. Such a system is simulated and a preliminary economic analysis performed. The results indicate that the vapor-compression system can collect almost 50% more solar energy than a conventional system if the collector area of the two systems are the same.