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Fluid distribution and investigation of heat transfer on a new type of solar flat-plate collector STAR Global Conference Vienna 2014 M.Eng. Pascal Leibbrandt Institut fr Regenerative Energietechnik Fachhochschule Nordhausen

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STAR Global Conference – Vienna 2014 1

M.Eng. Pascal Leibbrandt Institut für Regenerative Energietechnik Fachhochschule Nordhausen – University of Applied Sciences

Fluid distribution and investigation of heat transfer

  • n a new type of solar flat-plate collector

– STAR Global Conference – Vienna 2014

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STAR Global Conference – Vienna 2014 2

About us ...

The institute

  • founded in 2008
  • 20 employees (professors, academical and research staff)

Courses of study

  • renewable energy technology (B.Eng.)
  • economics engineering for sustainable technologies (B.Eng.)
  • systems engineering (M.Eng.)

Research

  • photovoltaic systems
  • flow machines
  • rotor blade optimization
  • circular processes (ORC) with membrane engine
  • hydrogen combustion
  • cooling of electric motors
  • mixed pellets
  • thermal energy storage optimization
  • energy concepts for special constructions/buildings
  • collector development

Laboratories

  • photovoltaic
  • power and operating machines
  • electrical energy systems
  • biomass, new energy sources
  • thermal energy systems
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Agenda The Project First Investigations Heat Transfer Fluid Flow Structural Analysis Outlook

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The Project

Motivation

  • Stagnation of the thermal collectors market for since 2008
  • Necessary to reduce system cost
  • Metallic absorber (copper, copper / aluminum, continuous casting)

have largest costs in materials and manufacturing technology Objectives

  • Collector redevelopment of insulating glass in the absorber and the

frame area

  • Target height < 50mm
  • Reduced material and production costs
  • Simpler manufacturing and assembly
  • Same performance as standard flat-plate collector
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The Project Construction

Coating (31) – low emission Fluid Structure (43) Coating (53b) – low emission Frame (90) Bonding (81) Sealing (82) Inlet (41) Outlet (42) Coating (11) – anti reflex Gas (60) Fluid (40) Glass (70) Glass (50) Glass (30) Glass (10) Gas (20) Inlet Structure (43a) Coating (13) – anti reflex Coating (53a) – high absorption

10 2.4 15 2.4 ~ 50 2.4 2.4 15

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Agenda The Project First Investigations Heat Transfer Fluid Flow Structural Analysis Outlook

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l s Top Back Front Bottom ϕ

Heat Transfer Problem

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Ideal Gas Real Gas Van der Waals

  • expression of density as a function of temperature and pressure
  • specific gas constant
  • at high pressure and high temperature gas behavior deviates

from ideal gas

  • ideal gas equation is specified:

p is replaced by (p+a/v²) v is replaced by (v-b)

  • a is a measure of attractive forces
  • b is the co-volume of particles
  • R=RU/ M

a ,b= f (RU ,T C , pC)

Heat Transfer Gas models

ρ= p RT RuT=( p+a/v

2)(v−b)

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Heat Transfer Experiment (Hollands)

Pressure Vessel Tube Grid Heater Aluminium Foil Tube Grid Copper Plates (56x61x1cm) Air Layer Thermocouples Screws Frame Rollers Cold Water In Hot Water In

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NuBF=1+1,44⋅(1−1708⋅ (sin(1,8⋅ϕ))

1,6

Ra⋅cosϕ

)[1−

1708 Ra⋅cosϕ]

p

+[( Ra⋅cosϕ 5830 )

1/3

−1]

p

Heat Transfer Experiment Solution

1 2 3 4 5 6 7 Nu

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Heat Transfer CFD Model

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Heat Transfer Mesh

Name

Trimmer PH + PLM PH + PLM-2 Models Trimmer Polyhedral Mesher + PLM Polyhedral Mesher + PLM Base Size 0,5 mm 0,5 mm 0,25 mm Cells 20.000 50.591 100.195

Trimmer PH + PLM-2

s s

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50°C 70°C 30° 45° 60°

Heat Transfer Scalar Scenes - Trimmer

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50°C 50°C 50°C 70°C 70°C 70°C 30° 45° 60°

Heat Transfer Scalar Scenes - Polyhedral+PLM

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Heat Transfer Solution

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Agenda The Project First Investigations Heat Transfer Fluid Flow Structural Analysis Outlook

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Fluid Flow Problem

Glass (30) Glass (50) Fluid (40) m'

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Fluid Flow Problem

Version 03 (Ref)

1412 mm 707/2 mm

Version 04 (Neg)

1412 mm 707/2 mm 100 mm 20 mm 100 mm 1412 mm 707 mm 100 mm 40 mm 100 mm Velocity Inlet (V' = 10 … 80 l/m²/h, 20°C) Wall (No-Slip, Adiabat) Pressure Outlet (101325 Pa, 20°C)

Sym.

SSDu=√

∑f (uf−̄

u)

2 Af

∑f A f

̄ u uf uf=̄ u→SSDu=0 uf=̄ u→SSDu>0

Top View

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Version 07 1412 mm 707/2 mm 100 mm 20 mm 100 mm 50 mm 5x40 mm s=5mm Version 08 1412 mm 707/2 mm 100 mm 20 mm 100 mm 50 mm 5x40 mm s=5mm 30 mm Version 09 1412 mm 707/2 mm 100 mm 20 mm 100 mm 50 mm 5x5 mm s=5mm Version 06 1412 mm 707/2 mm 100 mm 20 mm 100 mm 50 mm 5x40 mm s=10mm Version 07_01 1412 mm 707/2 mm 100 mm 20 mm 100 mm 50 mm 5x40 mm s=5mm 50 mm Version 06_10 1412 mm 707/2 mm 100 mm 20 mm 100 mm 50 mm 5x40 mm s=10mm 50 mm

SSDu=√

∑f (uf−̄

u)

2 Af

∑f A f

Fluid Flow Versions

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Fluid Flow Mesh

Wall Boundary Layer (PLM) Inlet Sym Wall Wall Sym

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V04 V06_01 V06

Fluid Flow Solution

Position in mm

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Fluid Flow Solution

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Pressure drop

Fluid Flow Solution

SSD in m/s

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Agenda The Project First Investigations Heat Transfer Fluid Flow Structural Analysis Outlook

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V02 Top=Free Bottom=5bar

Fixed Free Fixed Free

V01 Top=Free Bottom=5bar

Fixed Fixed Fixed Fixed

V04 Top=Free Bottom=5bar 10x10 Fixed

Fixed Fixed Fixed Fixed

V03 Top=Free Bottom=5bar

Free Fixed Free Fixed

Structural Analysis Problem

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Structural Analysis Solution

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Structural Analysis Solution

Pressure in Pa Pressure in Pa

Variation of Pressure Variation of Thickness p = 1bar

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Agenda The Project First Investigations Heat Transfer Fluid Flow Structural Analysis Outlook

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Outlook

Fluid Flow

  • Optimization of In- and Outlet geometry
  • Development of fluid-flow-structure regarding to heat transfer and pressure drop
  • Connection port – inlet – fluid-flow-structure (3D simulations)
  • Heat transfer in the gas layers (3D simulations)

Radiation

  • Disk assembly (distance, thickness) and functional coatings (AR, low-e, Absorption)
  • Examination by means of ray tracing and CFD by using thermal loads

Thermal Model

  • Heat loss on edge seal and collector connectors
  • Estimate thermal loads on glasses, sealants and adhesives

Structure

  • Optimization of edge bond and restraints
  • Structural analysis of sandwich glasses (30) and (50) with fluid-flow-structure
  • Reduction of glass mass

Experiment

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Thank you for your attention

Pascal Leibbrandt, M.Eng. Institut für Regenerative Energietechnik Fachhochschule Nordhausen – University of Applied Sciences www.fh-nordhausen.de/inret.html