vr_flyer_2013_englisch_final_801.pdf

8/14/2019 vr_flyer_2013_englisch_final_801.pdf

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Vacuum tubesMade in Germany

high performance

long lifetimeintrinsic safety heat pipe


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Manufacturing

NARVA was established in 1966 as part of the Berliner Glhlampenwerk, a lamp manufacturer. Fluorescentlamps have been manufactured in Brand-Erbisdorf near Dresden since that time. Since 1972 the glass tu-bes required for this have been produced in the companys own glass works. A total of 30 million fluore-scent lamps now leave the plant each year.

Expertise in the fields of glass production, vacuum technology and coating technology as well as aware-ness of sustainability and the environment led NARVA to the area of solar thermal applications. Know-howin the technically highly similar processes has subsequently reduced the development time of NARVA va-cuum tubes to just two years.

2007 saw the first vacuum tubes with direct flow leave the fully-automated production line. NARVA workscontinuously to increase the effi ciency of the vacuum tubes. The result is multiple trademarks and ahigh-performance heat pipe with a particularly high level of effi ciency. This is especially attractive for theyields of process heat.

In its capacity as an OEM supplier, NARVA currently offers vacuum tubes in the following layouts:

direct flow vacuum tubes

heat pipe vacuum tubes

Both models are available with absorber coated on one or both sides (type standard or power) and in thelengths 800 mm, 1,500 mm, 1,775 mm and 2000 mm.


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Process heat

Woodstock, CanadaLodz, PolandRottweil, Germany

It is in the field of process heat that solar thermal applications with vacuum tubes reveal their real strengths.If the heat requirements of the process are always higher than the maximum output of the solar collectors,the system benefits from the high degree of efficiency of the direct flow NARVA vacuum tubes. If the sys-tem is dimensioned towards maximum solar fraction, then a customer-specific temperature limit can beachieved via the intrinsically safe NARVA heat pipe.

In Germany companies receive subsidies of 50% of the investment costs(Bafa and KfW) when using solar thermal applications for the generationof process heat.

The use of solar heat as an energy source for process heat stands at the beginning of a steep developmentcurve:

The example of Denmark illustrates what effects can result from the consistent expansion of electricity

generation from wind and PV: combined heat and power plants are only used to fill gaps in generation.

Less and less combined heat and power generation is required with the further expansion of wind andsolar power plants. This creates space for the solar-thermal generation of local heat.Denmark is leading the way with a market growth of 80%. In order to extend this trend beyond Denmarknew collectors have to be planned for high annual solar fractions.

Vacuum collector tubes are a necessary basis for this.


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Solar heating

Hotel, CroatiaPrivate home , GermanyTracker system, Austria

A frequent operational status in heating and hot water generation is a high loading temperature of thestorage tank. This temperature level must be exceeded by the solar unit. Due to their low emission loss andhighly rapid response, NARVA vacuum tubes are particularly well-suited to transporting heat to the storagetank at a temperature level of over 90C.

In the scope of the German commercialisation programme launched in summer 2012 the minimum fun-ding rate stands at 1,500 per newly-installed solar heating unit.

Heat diversion pipe and absorber are located in a vacuum in NARVA tubes. This means

that they are not exposed to ambient influences and are protected against aging whichguarantees a long lifetime.

At a temperature difference between the heat transfer fluid and ambient temperature of just 25 Kelvin thevacuum tube collector already achieves higher annual yields than the flat plate collector.

Annual yield comparison

between vacuum tubecollector andflat plate collector (grosssurface area)

vacuum tubeflat plate collector

temperature difference to environment / K

W /kWh/(m x a)


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Thermosyphon systems

Thermosyphon systems are primarily utilised in the Mediterranean region and are available in two techni-cal setups:

Thermosyphon systems with integrated condenser in buffer storage

Thermosyphon systems with a separate collector and buffer storage

With NARVA heat pipe vacuum tubes the system is intrinsically safe. The limitation of temperature via spe-cial evaporator fluid prevents vapour shocks when drawing from the outlets.

Environmental influences such as wind or low ambient temperatures have no influence on the yield of the

vacuum tube collectors. Electronic controls and pumps are not necessary, this makes the system less proneto breakdown and require less maintenance.

Collectors with NARVA heat pipe vacuum tubes have a significantly higher degree of effi-ciency compared to flat plate collectors. In combination with the temperature limitationthey are ideally suited for use in siphon systems.

Private Home, SlovakiaPrivate Home, GermanyPrivate Home, Italy

Power output of tube collectorat solar radiation of 1000 W/m

(collector with 10 tubes)

Collectoroutput W/m

working fluid temperature / C


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NARVA technology guarantees intrinsic safety:

Cladding tube

Wellenlnge (nm)

100

98

96

94

92

90

88

86

84

82

80

Transmissionsgrad(%)

NARVA-Glas mit ARS

NARVA-Glas unbeschichtet

300 400 500 600 700 800 900 1000 1100

NARVA heat pipe tubes are ideally suited for a wide range of solarthermal applications from thermalsy-phons systems, solar heating to process heat. This is due to a customised cut-off behaviour developedby NARVA.

Smudge-proof coating of the cladding tube with nano particles increases the transparency of the glass to

up to 96% in the transmission characteristic maximum. In addition, the coating also protects against we-athering of the glass surface. The relatively large wall thickness and the coating enables the tube to achievea high level of hail resistance (hail strike test as per EN 12975-2 TV Rheinland).

Technical information

cut-off behaviorin function stagnation

Power output of tube collectorat solar radiation of 1000 W/m

(collector with 10 tubes)

wavelength (nm)

transmittance(%)

NARVA glass with ARS coatingNARVA glass uncoated

Collectoroutput W/m

working fluid temperature / C


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Technical information

Over 20 years of stable vacuum insulation

No damage to or aging of the absorber TiNOX-coating with best absorption and emission parameters

Optimum transmission values through anti-reection double coating

Highly robust and patented glass-metal-connection

Break-proof under heavy snow loads

Behaves like safety glass in case of forcible destruction

NARVA vacuum tubes

direct flow

NARVA vacuum tubes

heat pipe

Nominal length LT (mm) 800 1.500 1.775 2.000 800 1.500 1.775 2.000

Tube length (mm) 810 1.510 1.785 2.010 810 1.510 1.785 2.010

Diameter of glass tube (mm) 56 56

Apertureface of glass tube (m) 0,0386 0,0750 0,090 0,1010 0,0386 0,0750 0,090 0,1010

nominal tube output (W)at an irradiance of 1,000 W/m

30 59 71 80 28 56 67 76

Absorbed heat at 1,000 kWh/a*m

temperature difference 40K (KWh/a) 27 53 64 72 25 50 60 68

Absorbed heat at 1,000 kWh/a*mtemperature difference 100K (KWh/a)

23 45 54 61 21 42 50 57

Heat transmission coeffi cient linear(W/m*K)

1,12 1,12

Heat transmission coeffi cient quadratic(W/m*K)

0,004 0,004

Effi ciency factor 0,781 0,750

Direct flow vacuum tubes:

Usable in continuous operation due to their at characteristic line, up to a heat transfer tempera-ture of 150 C

full all requirements under DIN EN 12975-2 (Thermal solar systems and components - Solar collectors - Part 2: Test methods)

Designed for a lifetime of 20 years Stagnation temperature: up to 300C if there is a risk of frost a corresponding heat transfer substance is to be used

Heat pipe:

Variable cut-off at 130 C to 160 C according to customer specication

Works in vertical position and up to an angle of 12 without loss of performance Satises all requirements under DIN EN 12975-2 Designed for a lifetime of 20 years Frost-proof

Operating instructions

Technical data

all data valid for type Standard (absorber one side coated)


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NARVA Lichtquellen GmbH + Co. KG | Industriegebiet Nord | Erzstrae 22 | D-09618 Brand-ErbisdorfTel.: +49 (0)3 73 22/ 1 72 00 | Fax: +49 (0)3 73 22/ 1 72 03 | Internet: www.narva-bel.de | E-Mail: offi [email protected]

NARVA

LichtquellenGmbH+Co.

KG

2013

.06

Product overview

Direct flow vacuum tubesAbsorber

coating

Length

mm

connection

length mmPU Order no.

VR 800 Standard one side 800 57 10 1301 0003

VR 1500 Standard one side 1.500 57 10 1301 0002



VR 800 Power both sides 800 57 10 1301 0012

VR 1500 Power both sides 1.500 57 10 1301 0014



Heat pipe vacuum tubes

Absorber

coating

Length

mm

connection

length mmPU Order no.

VR 800 Standard one side 800 30,5 10 1302 0007

VR 1500 Standard one side 1.500 30,5 10 1302 0008



VR 800 Power both sides 800 30,5 10 1302 0004

VR 1500 Power both sides 1.500 30,5 10 1302 0006



Heat pipes are available without cladding tube on request.

Documents

vr_flyer_2013_englisch_final_801.pdf