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![Page 1: Novel Design of a Portable Heat Energy Storage Device Adopting a Phase Change Material for CHP and Solar Energy Applications K. TRAPANI BSc. Renewable.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5518be6b550346a61f8b5477/html5/thumbnails/1.jpg)
Novel Design of a Portable Heat Energy Storage Device Adopting a
Phase Change Material for CHP and Solar Energy Applications
K. TRAPANI
BSc. Renewable Energy Final Year Dissertation
Project Supervisor: Dr. Dean Millar
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INTRODUCTION
Concept: Extraction of waste heat
from an automotive micro-CHP engine using a portable
thermal storage device (Millar & Huang, 2009)
Specific design of the portable thermal energy storage adopting phase
change materials (PCMs)
![Page 3: Novel Design of a Portable Heat Energy Storage Device Adopting a Phase Change Material for CHP and Solar Energy Applications K. TRAPANI BSc. Renewable.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5518be6b550346a61f8b5477/html5/thumbnails/3.jpg)
•Compact•Light
•Modular•Stackable
•High thermal energy storage•Efficient heat transfer
REQUIREMENTS OF THE DEVICE
PORTABILITY
FLEXIBLE THERMAL CAPACITY
MAXIMISED PERFORMANCE
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DEVICE DESIGN
Modular unit:Mass = 15kgDimensions = 20cm x 35cm x 18cm
Model unit (1/5th scale):Mass = 3kgDimensions = 12cm x 35cm x 6cm
Component Material
PCM Paraffin waxPiping CopperFins Aluminium
Internal case SteelInsulation Reflective foam
External case Plastic
SOLIDWORKS DESIGN OF A 1/5th SCALE MODEL
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PCMs – materials which exhibit a phase change (from one state to another)
PHASE CHANGE MATERIALS (PCMs)
STATES
GAS
LIQUID
SOLID
Enth
alpy
of S
yste
m
TEM
PERA
TURE
ENTHALPY
SOLID
LIQUID
GASPHASE CHANGE
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PHASE TRANSITIONS
SELECTION OF DEVICE’S PCM
SOLID-LIQUID
SOLID-SOLID
SOLID-GAS
GAS-LIQUID
SOLID-LIQUID
ORGANICS INORGANICS• Not corrosive• Low or no undercooling• Chemically and thermally ostable
• Greater phase change oenthalpy
Paraffin Wax
Relatively high heat of fusion
Stable heating and cooling cycle
Economical and abundant
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PROPERTIES OF THE DEVICE’S PCMDensity, ρ (solid) 896 kg/m3
Density, ρ (liquid) 820 kg/m3
Melting temperatures, T 328K – 330K
Specific heat capacity, cs 3412 J/kgK
Specific heat capacity, cl 4466 J/kgK
Latent heat of fusion, L 197 kJ/kg
0 500 1000 1500 2000 2500 3000 3500 40000
10
20
30
40
50
60
Time (s)
Tem
pera
ture
(deg
C)
Where Q = Pt
Governing equations:
Q = mc∆ϴ
Q = mL
Sensible heating
Latent heating
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SIMULATION
Simulation software had to be modelled to account for the phase change material.
Assumptions:• Paraffin wax is homogenous and isotropic• Heat is transferred only by conduction• Simulation is time dependent
Hence the paraffin wax’s thermal properties had to be designed as a series of sensible heating stages.
Cs = 3412J/kgK for T<328K
Csl = 98587J/kgK for 328K<T<330K
Cl = 4466J/kgK for T>330K
Boundary conditions:• Mass flow rate of heat transfer medium 0.108kg/s at 333.2K• Fluid outlet subject to normal environmental conditions (293.2K and 101325Pa)
Initial conditions:• Same as normal environmental conditions
Results (for a model scale device):
• Thermal heat capacity – 381.7kJ
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TESTING OF 1/5th SCALE PROTOTYPE
“CHARGING” of Device: “DISCHARGING” of Device:
Heat supplied thermal store = 595.8kJ
η = 64.1%
Heat retrieved from thermal store = 247.0kJ
η = 64.7%Overall efficiency =
41.5%
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The device is primarily designed to be integrated with a central domestic heating system.
DEVICE INTEGRATION
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The main heat sources for the device are:• Micro – CHP (automotive vehicle engines)• Surplus solar thermal heat
APPLICATIONS FOR THE DEVICE
Micro-CHP Solar
• Requires a portable heat transfer medium•Integration with an automotive vehicle
• Stationary application• Integration with the domestic central heating systemTwo primary heat sources:
• Exhaust gas• Engine cooling process
Yu, C., & Chau, K.T. (2009) Review on thermal energy storage with phase change. Renewable and Sustainable Energy Reviews, 13, 318 – 345.
Retrieved from duaemanus.blogspot.com
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OVERVIEW OF A MICRO-CHP INTEGRATED DEVICE
Increase mass implies:
• a larger CAPEX• greater operating costs
• enhanced revenue
Scenarios
Displacement of gas heating
Displacement of electricity heating
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• Main application for device is in micro-CHP
• Economically device is currently not very feasible for displacing the heating load from a gas boiler
• Optimisation of the design (improving PCM to total device mass ratio)
• Simulation testing for practical maximum efficiency
• Consequent optimisation of the practical model
• Further development of device fittings is crucial to the installation of the device
CONCLUSION
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THANK YOU
ANY QUESTIONS?