Parabolic Trough Receiver Thermal Testing

2007 ◽  
Author(s):  
Frank Burkholder ◽  
Michael Brandemuehl ◽  
Henry Price ◽  
Judy Netter ◽  
Chuck Kutscher ◽  
...  
Keyword(s):  
Heat Loss ◽  
Operating Temperature ◽  
Thermal Testing ◽  
Published Data ◽  
Thermal Loss ◽  
Performance Parameters ◽  
Parabolic Trough ◽  
Receiver Performance ◽  
The Difference ◽  
Indoor And Outdoor

NREL has fabricated a parabolic trough receiver thermal loss test stand to quantify parabolic receiver off-sun steadystate heat loss. At an operating temperature of 400°C, measurements on Solel UVAC2 and Schott PTR70 receivers suggest off-sun thermal losses of approximately 370 W/m receiver length. For comparison, a receiver from the field with hydrogen in its annulus loses approximately 1000 W/m receiver length. The UVAC2 heat loss results agree within measurement uncertainty to previously published data, while the PTR70 results are somewhat higher than previously published data. The sensitivity of several receiver performance parameters is considered and it is concluded that differences in indoor and outdoor testing cannot account for the difference in PTR70 thermal loss results.

scholarly journals Generation of a Parabolic Trough Collector Efficiency Curve From Separate Measurements of Outdoor Optical Efficiency and Indoor Receiver Heat Loss

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Charles Kutscher ◽  
Frank Burkholder ◽  
J. Kathleen Stynes
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Thermal Efficiency ◽  
Operating Temperature ◽  
Efficiency Curve ◽  
Parabolic Trough ◽  
Optical Efficiency ◽  
Parabolic Trough Collector ◽  
Collector Efficiency ◽  
The Difference

The thermal efficiency of a parabolic trough collector is a function of both the fraction of direct normal radiation absorbed by the receiver (the optical efficiency) and the heat lost to the environment when the receiver is at operating temperature. The thermal efficiency can be determined by testing the collector under actual operating conditions or by separately measuring these two components. This paper describes how outdoor measurement of the optical efficiency is combined with laboratory measurements of receiver heat loss to obtain the thermal efficiency curve. This paper describes this approach and also makes the case that there are advantages to plotting collector efficiency versus the difference between the operating temperature and the ambient temperature at which the receiver heat loss was measured divided by radiation to a fractional power (on the order of 1/3 but obtained via data regression)—as opposed to the difference between operating and ambient temperatures divided by the radiation. The results are shown to be robust over wide ranges of ambient temperature, sky temperature, and wind speed.

Experimental Analysis of Overall Thermal Properties of Parabolic Trough Receivers

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Eckhard Lüpfert ◽  
Klaus-J. Riffelmann ◽  
Henry Price ◽  
Frank Burkholder ◽  
Tim Moss
Keyword(s):  
Thermal Properties ◽  
Experimental Analysis ◽  
Operating Temperature ◽  
Field Measurements ◽  
Heat Losses ◽  
Thermal Loss ◽  
Parabolic Trough ◽  
Energy Balances ◽  
Good Agreement ◽  
Glass Envelope

The heat loss of a receiver in a parabolic trough collector plays an important role in collector performance. A number of methods have been used to measure the thermal loss of a receiver tube depending on its operating temperature. This paper presents methods for measuring receiver heat losses including field measurements and laboratory setups both based on energy balances from the hot inside of the receiver tube to the ambient. Further approaches are presented to measure and analyze the temperature of the glass envelope of evacuated receivers and to model overall heat losses and emissivity coefficients of the receiver. Good agreement can be found between very different approaches and independent installations. For solar parabolic trough plants operating in the usual 390°C temperature range, the thermal loss is around 300W∕m receiver length.

scholarly journals Prognostic Assessment of the Performance Parameters for the Industrial Diesel Engines Operated with Microalgae Oil

2021 ◽  
Vol 13 (11) ◽  
pp. 6482
Author(s):  
Sergejus Lebedevas ◽  
Laurencas Raslavičius
Keyword(s):  
Energy Efficiency ◽  
Diesel Engine ◽  
High Speed ◽  
Performance Parameters ◽  
Prognostic Assessment ◽  
High Speed Diesel ◽  
Microalgae Oil ◽  
The Difference ◽  
Smoke Opacity ◽  
Efficiency Indicators

A study conducted on the high-speed diesel engine (bore/stroke: 79.5/95.5 mm; 66 kW) running with microalgae oil (MAO100) and diesel fuel (D100) showed that, based on Wibe parameters (m and φz), the difference in numerical values of combustion characteristics was ~10% and, in turn, resulted in close energy efficiency indicators (ηi) for both fuels and the possibility to enhance the NOx-smoke opacity trade-off. A comparative analysis by mathematical modeling of energy and traction characteristics for the universal multi-purpose diesel engine CAT 3512B HB-SC (1200 kW, 1800 min−1) confirmed the earlier assumption: at the regimes of external speed characteristics, the difference in Pme and ηi for MAO100 and D100 did not exceeded 0.7–2.0% and 2–4%, respectively. With the refinement and development of the interim concept, the model led to the prognostic evaluation of the suitability of MAO100 as fuel for the FPT Industrial Cursor 13 engine (353 kW, 6-cylinders, common-rail) family. For the selected value of the indicated efficiency ηi = 0.48–0.49, two different combinations of φz and m parameters (φz = 60–70 degCA, m = 0.5 and φz = 60 degCA, m = 1) may be practically realized to achieve the desirable level of maximum combustion pressure Pmax = 130–150 bar (at α~2.0). When switching from diesel to MAO100, it is expected that the ηi will drop by 2–3%, however, an existing reserve in Pmax that comprises 5–7% will open up room for further optimization of energy efficiency and emission indicators.

Determination of Resistance to Abrasive Wear. VIII. Influence of Softeners in Tests with the Akron-Croydon and Du Pont Machines

1949 ◽  
Vol 22 (1) ◽  
pp. 259-262
Author(s):  
J. F. Morley
Keyword(s):  
Unit Area ◽  
Published Data ◽  
The Road ◽  
Abrasive Surface ◽  
Abrasive Power ◽  
The Difference ◽  
On The Road ◽  
The Right ◽  
Abrasion Testing

Abstract These experiments indicate that softeners can influence abrasion resistance, as measured by laboratory machines, in some manner other than by altering the stress-strain properties of the rubber. One possible explanation is that the softener acts as a lubricant to the abrasive surface. Since this surface, in laboratory abrasion-testing machines, is relatively small, and comes repeatedly into contact with the rubber under test, it seems possible that it may become coated with a thin layer of softener that reduces its abrasive power. It would be interesting in this connection to try an abrasive machine in which a long continuous strip of abrasive material was used, no part of it being used more than once, so as to eliminate or minimize this lubricating effect. The fact that the effect of the softener is more pronounced on the du Pont than on the Akron-Croydon machine lends support to the lubrication hypothesis, because on the former machine the rate of wear per unit area of abrasive is much greater. Thus in the present tests the volume of rubber abraded per hr. per sq. cm. of abrasive surface ranges from 0.03 to 0.11 cc. on the du Pont machine and from 0.0035 to 0.0045 cc. on the Akron-Croydon machine. On the other hand, if the softener acts as a lubricant, it would be expected to reduce considerably the friction between the abrasive and the rubber and hence the energy used in dragging the rubber over the abrasive surface. The energy figures given in the right-hand columns of Tables 1 and 3, however, show that there is relatively little variation between the different rubbers. As a test of the lubrication hypothesis, it would be of interest to vary the conditions of test so that approximately the same amount of rubber per unit area of abrasive is abraded in a given time on both machines; this should show whether the phenomena observed under the present test conditions are due solely to the difference in rate of wear or to an inherent difference in the type of wear on the two machines. This could most conveniently be done by considerably reducing the load on the du Pont machine. In the original work on this machine the load was standardized at 8 pounds, but no figures are quoted to show how abrasion loss varies with the load. As an addition to the present investigation, it is proposed to examine the effect of this variation with special reference to rubbers containing various amounts and types of softener. Published data on the influence of softeners on the road wear of tire rubbers do not indicate anything like such large effects as are shown by the du Pont machine. This throws some doubt on the value of this machine for testing tire tread rubbers, a conclusion which is confirmed by information obtained from other workers.

scholarly journals Composite Distribution Solution for Minimizing Heat Loss in a Pyrolysis Reactor

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Werner O. Filtvedt ◽  
Morten Melaaen ◽  
Arve Holt ◽  
Massoud Javidi ◽  
Birger Retterstøl Olaisen
Keyword(s):  
Heat Loss ◽  
Reaction Chamber ◽  
Inlet Temperature ◽  
Chemical Reactors ◽  
Normal Procedure ◽  
Pyrolysis Reactor ◽  
The Difference ◽  
Distribution Plate ◽  
Composite Distribution ◽  
Novel Design

The article presents a novel design for a distribution plate. The solution is suitable for a reactor vessel where a reactant gas needs to be maintained at a different temperature from the reaction chamber in order to avoid unwanted occurrences, such as clogging of the distribution plate. A normal procedure involves cooling of the distribution plate which is reported to either increase heat loss substantially or yield insufficient temperature in parts of the reaction chamber. The problem is especially important for reactors where the difference in reactant inlet temperature and desired reaction temperature is large. The investigated design utilized materials of very different thermal conductivity to only cool specific parts of the distribution arrangement and thereby minimize heat loss. Our system is a distribution plate for use in a fluidized bed reactor for silane pyrolysis. However, the solution is general and may be utilized in many types of vessels and chemical reactors.

Variation in Skin Cancer Pattern in the Southwestern Region of Pakistan

2021 ◽  
Vol 15 (12) ◽  
pp. 3402-3404
Author(s):  
Hina , Manzoor ◽  
Najeeb Ahmad ◽  
Zafar H Tanveer ◽  
Khush Naseed Ahmed ◽  
Munir , Ahmed ◽  
...  
Keyword(s):  
Squamous Cell Carcinoma ◽  
Skin Cancer ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Published Data ◽  
Non Melanoma Skin Cancer ◽  
Broad Term ◽  
The Difference ◽  
Field Workers ◽  
Melanoma Skin

Background: Skin cancer is a broad term that refers to a variety of different types of cancer. It is usually recognized as non-melanoma and melanoma skin cancer. In many parts of the world, the prevalence is high, with significant ecological and ethical variation. Objectives: Objective was to determine demographic and histological features of skin cancer in Southwest region of Pakistan. Methodology: This retrospective study was carried out on skin cancer 1169 cases of Centre for Nuclear Medicine and Radiotherapy (CENAR) in Quetta. The data from January 2000 to December 2009 (10Years) was retrieved from record. The aim was to determine the importance of skin cancer in this area, its gender wise distribution and its pathological types. Results: Record of total 9308 cancer patients was retrieved from patients presenting to CENAR Quetta. From 9308 case, 1169(12.5%) patients were of skin cancer which was second most prevalent category of cancer in this area. Prevalence was higher in males with 713(61%) cases as compared to females. Pathologically with 634(54%) cases, the most prevalent category was Squamous cell carcinoma (SCC). Conclusion: Skin cancer is wide-spread type of cancer in patients of south-west region of Pakistan. The findings of this study are not aligned with published data. The difference is because of high altitude of the study area, dry climate and long skin exposure particularly in low socio-economic field workers. Keywords: Skin cancer, gender, Melanoma skin cancer (MSC), Squamous cell carcinoma (SCC), Non-melanoma skin cancer (NMSC), Basal cell carcinoma (BCC),

scholarly journals Anterior Cervical Corpectomy and the Operating Team: A Controversy?

2018 ◽  
Vol 07 (01) ◽  
pp. 008-015
Author(s):  
Alexandrina Nikova ◽  
Theodossios Birbilis
Keyword(s):  
Cervical Myelopathy ◽  
Postoperative Outcome ◽  
Published Data ◽  
Multifactorial Disease ◽  
Surgical Team ◽  
Cervical Corpectomy ◽  
Operating Team ◽  
Anterior Corpectomy ◽  
The Difference ◽  
Anterior Cervical Corpectomy

AbstractCervical myelopathy is multifactorial disease that can lead to many dysfunctions. Surgical treatment is believed to be the best healing choice. The authors searched the published data on Medline on this subject and found a difference between the neurosurgeons and orthopaedics on the topic of anterior corpectomy for cervical myelopathy. The difference between the orthopaedics and neurosurgeons is not big, but it could be relevant to the final outcome, which appears to be better in the neurosurgeons. The complication rate is also variable between the groups, with lower rates of complication reported by the neurosurgeons. Therefore, despite the fact that the postoperative outcome depends on many factors, such as preoperative condition, additional comorbidities, age, and lifestyle, this article also finds that the surgical team, after comparing basic techniques that the team used for anterior cervical corpectomy (ACC), is also responsible to some extent. This, however, is not a competition, and future cooperation between the teams might be beneficial for all.

scholarly journals On the Non-Specific Stimulation of Agglutinins. With Especial Reference to the Enteric Fevers and Typhus Fever

1929 ◽  
Vol 28 (4) ◽  
pp. 418-448 ◽  
Author(s):  
A. Felix
Keyword(s):  
Qualitative Method ◽  
Published Data ◽  
Enteric Infection ◽  
Widal Test ◽  
Enteric Infections ◽  
The Difference ◽  
Specific Stimulation ◽  
Enteric Group ◽  
Typhus Fever ◽  
Stimulation Of

(1) The review of the published data furnishes additional evidence in support of the view that no technique whatsoever, Dreyer's technique included, based on the quantitative method of the agglutination reaction hitherto used, is capable of affording a differentiation between inoculation and infection agglutinins.(2) These techniques are concerned always exclusively in the demonstration of the labilotropic H agglutinins ofB. typhosusandB. paratyphosusA. and B. and it is the behaviour of these agglutinins that is the responsible factor in producing the phenomena.(3) In various febrile conditions in inoculated individuals these H agglutinins undergo a re-stimulation resulting in a curve of agglutination which is indistinguishable from that due to specific stimulation. The re-stimulation of the labilotropic inoculation agglutinins is of the same nonspecific character (i.e.heterologous) in the course of enteric infections as in the course of other febrile diseases.(4) The observation of this non-specific re-stimulation is independent of the technique used; living bacilli and suspensions preserved with phenol or formalin (Dreyer's technique included) do not in this respect behave differently.(5) The proposed qualitative method for the Widal test depends, in inoculated individuals, exclusively upon the behaviour of the stabilotropic O agglutinins. In their presence it is capable of affording the certain diagnosis of an enteric infection; in their absence the negative result of the test is not conclusive; if T.A.B. vaccine has been used it is only possible to diagnose enteric group without being able to differentiate typhoid from paratyphoid A. or B.; if T. vaccine has been used then A. or B. infection can be differentiated but not T.(1) The conclusions previously arrived at by means of the qualitative method of the Widal test were fully confirmed. By eliminating the labilotropic H agglutinins from any consideration—in the case of previously sensibilised individuals—agglutination due to the specific stimulation in active enteric infection can be distinguished definitely from that due to the nonspecific re-stimulation by various febrile diseases.(2) Normal and immune O agglutinins forB. typhosusandB. paratyphosusA. and B., as well as those forB. proteusX 19, are not liable to non-specific stimulation in the course of various febrile diseases.(3) One more of the supposed differences in nature between the Widal test and the Weil-Felix test is thereby eliminated.(4) The difference in the response to non-specific stimulation shown to exist in stabilotropic and labilotropic agglutination seems more likely to be one of degree than one in nature and needs further investigation.

scholarly journals Comparison of direct and geodetic mass balances on a multi-annual time scale

2010 ◽  
Vol 4 (3) ◽  
pp. 1151-1194
Author(s):  
A. Fischer
Keyword(s):  
Mass Balance ◽  
Direct Method ◽  
Mean Difference ◽  
Published Data ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
Direct Data ◽  
The Mean ◽  
The Difference ◽  
Geodetic Mass Balance

Abstract. Glacier mass balance is measured with the direct or the geodetic method. In this study, the geodetic mass balances of six Austrian glaciers in 19 periods between 1953 and 2006 are compared to the direct mass balances in the same periods. The mean annual geodetic mass balance for all periods is −0.5 m w.e./year. The mean difference between the geodetic and the direct data is −0.7 m w.e., the minimum −7.3 m w.e. and the maximum 5.6 m w.e. The accuracy of geodetic mass balance resulting from the accuracy of the DEMs ranges from 2 m w.e. for photogrammetric data to 0.002 m w.e. for LIDAR data. Basal melt, seasonal snow cover and density changes of the surface layer contribute up to 0.7 m w.e. for the period of 10 years to the difference to the direct method. The characteristics of published data of Griesgletscher, Gulkana Glacier, Lemon Creek glacier, South Cascade, Storbreen, Storglaciären, and Zongo Glacier is similar to these Austrian glaciers. For 26 analyzed periods with an average length of 18 years the mean difference between the geodetic and the direct data is −0.4 m w.e., the minimum −7.2 m w.e. and the maximum 3.6 m w.e. Longer periods between the acquisition of the DEMs do not necessarily result in a higher accuracy of the geodetic mass balance. Specific glaciers show specific trends of the difference between the direct and the geodetic data according to their type and state. In conclusion, geodetic and direct mass balance data are complementary, but differ systematically.

scholarly journals The mitochondrial ADP/ATP carrier exists and functions as a monomer

2020 ◽  
Vol 48 (4) ◽  
pp. 1419-1432 ◽  
Author(s):  
Edmund R.S. Kunji ◽  
Jonathan J. Ruprecht
Keyword(s):  
Conformational Changes ◽  
Membrane Vesicles ◽  
Native Mass Spectrometry ◽  
Published Data ◽  
Oligomeric State ◽  
Technical Errors ◽  
Density Maps ◽  
Mitochondrial Carrier Family ◽  
The Difference ◽  
And Function

For more than 40 years, the oligomeric state of members of the mitochondrial carrier family (SLC25) has been the subject of debate. Initially, the consensus was that they were dimeric, based on the application of a large number of different techniques. However, the structures of the mitochondrial ADP/ATP carrier, a member of the family, clearly demonstrated that its structural fold is monomeric, lacking a conserved dimerisation interface. A re-evaluation of previously published data, with the advantage of hindsight, concluded that technical errors were at the basis of the earlier dimer claims. Here, we revisit this topic, as new claims for the existence of dimers of the bovine ADP/ATP carrier have emerged using native mass spectrometry of mitochondrial membrane vesicles. However, the measured mass does not agree with previously published values, and a large number of post-translational modifications are proposed to account for the difference. Contrarily, these modifications are not observed in electron density maps of the bovine carrier. If they were present, they would interfere with the structure and function of the carrier, including inhibitor and substrate binding. Furthermore, the reported mass does not account for three tightly bound cardiolipin molecules, which are consistently observed in other studies and are important stabilising factors for the transport mechanism. The monomeric carrier has all of the required properties for a functional transporter and undergoes large conformational changes that are incompatible with a stable dimerisation interface. Thus, our view that the native mitochondrial ADP/ATP carrier exists and functions as a monomer remains unaltered.

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