Encouragement-22-Yang Zhaosheng

Performance of Composite Adsorbent Heat Exchanger with MetalFoam Coated with Hydrophilic Polymer
11, 21, 2Yang Zhaosheng , František MIKŠÍK , Kyaw Thu , Miyazaki Takahiko

1, 2

1

Interdisciplinary Graduate School of Engineering, Sciences, IGSES, Kyushu University, Fukuoka, Japan.
2International Institute of Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka, Japan.
Email: yang.zhaosheng.705@s.Kyushu-u.ac.jp
Keywords: Adsorption heat exchanger, Adsorbent coating, Metal Foam, Heat and mass transfer, dehumidification

Adsorption heat exchanger1

Metal foam is a porous metal material. It has emerged as apotential material for advanced heat exchangers in aircooling systems due to these advantages:

Adsorption technology is regarded as an environment-friendly approach for lowgrade thermal utilization, such as heat pumps, thermal energy storage anddehumidification etc.
The performance of this technology is highly affected by the heat and mass transfer
efficiency in the adsorption heat exchangers.
Metal-based additives
Increasing thermal
conductivity

Highlighted contact surface
Adsorbent particles
Fins
Tube wallMetal Foam2⚫
⚫

Carbon-based additives

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2

3

High surface area to volume ratio, 1000-3000 [m /m ]High conductivity of the solid struts, 200-400 [W/(m K)]
Enhanced flow mixing induced by the tortuous flow paths

Other additives

Methods to improve
the heat transferperformance

Increasing heattransfer areaFins
Fixed bed

Heat Transfer Fluid

Reducing thermal
contact resistance

Binder-based Coating
Crystallization Coating

Methodology

3◆ Adsorption dehumidification system with metal foam heat exchanger:◆ Based on the calculation domain, following

Metal Foam

governing equations are establishedTransition Duck
Straightener⚫

The mass balance in air layer
𝜕𝑋𝑎𝜕𝑋𝑎 ℎ𝑚= −𝑢𝑎+
𝑋𝑖 − 𝑋𝑎𝜕𝑡𝜕𝑥
δ𝑎Water outlet
Water inlet

Symmetry
Air inlet

InterfaceSymmetry𝜌𝑚𝑓𝑐𝑝,𝑚𝑓𝑘𝑚𝑓(kg m−3)(J kg−1 K−1)

(W m−1 K−1)

Aluminum

2680

900237

Copper

8954

385

401

Material
𝛿𝑎Composite Adsorbent

The energy balance in air layer
𝜕𝑇𝑎𝜕𝑇𝑎ℎ𝑎= −𝑢𝑎+𝑇𝑖 − 𝑇𝑎𝜕𝑡
𝜕𝑥 ρ𝑎 𝑐𝑝,𝑎 δ𝑎◆ Parameters of different metal foam

◆ Computational domain:Moisture Adsorption Adsorption Heat⚫

𝛿𝑏Iron

7870

44480

Nickel

8908

42794

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The mass balance in adsorption heat exchanger𝜕ρ𝑤 𝐷𝑏 𝜕 2 ρ𝑤 3𝐷𝑏ρ𝑠 1 − ε 𝜕𝑊=+ρ𝑖 − ρ𝑤 −22𝜕𝑡ζε 𝜕𝑥ε𝜕𝑡ζεδ𝑏⚫

The energy balance in adsorption heat exchanger
𝜕𝑇𝑏𝜕 2 𝑇𝑏 3α𝑏𝑞𝑎𝑑𝑠 ρ𝑠 ζ 1 − ε 𝜕𝑊
= α𝑏+ 2 𝑇𝑖 − 𝑇𝑏 +2𝜕𝑡𝜕𝑥
ρ𝑏 𝑐𝑝,𝑏𝜕𝑡δ𝑏LResults

4◆ The performance of composite adsorbent bed possessing metal foam andhydrophilic polymer coating were investigated through numerical simulations.
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Compared with other metal foams, the composite adsorption heat exchanger using aluminum
foam has higher SDP and COP.
High-porosity metal foam is recommended, because the SDP, DE and COP of the adsorbent bed
all increase with the increase of the porosity of the metal foam.

Stream tracer
Temperature variation
Stream Tracer & Temperature variation

Cross-section view – Velocity(a) Specific Dehumidification Power (SDP)(b) Dehumidification Effectiveness (DE)(c) Coefficient of Performance (COP)

Performance of Composite Adsorbent Heat Exchanger with Metal Foam Coated with Hydrophilic PolymerEncouragement-22-Yang Zhaosheng