this power point discuses about pcm material s and recently applications on green house and introduce kind of pcm system this power point priority created by some other authors

1. Preparation by Sajjad Hooshmandi
Performance of Phase Change
Material (PCM) Wall
Qazvin Islamic Azad
University

2. Trombe wall variation
 Zigzag Trombe wall
 Fluidized Trombe wall
 Trombe wall with phase-change material
 Composite Trombe wall
 Photovoltaic (PV) Trombe wall

3. Zigzag Trombe Walls
Purpose: To reduce excessive heat gain and glare in sunny days.
Construction & working[1]:
It consists of three sections
– One facing south other two sections forms a inward “V” shaped wall
– One section of V shaped wall faces south east provides light and heat during
morning times through windows when immediate heating is required.
– The opposite is a classical Trombe wall which stores heat during afternoon
time and supply heat in night times.

4. Fluidized Trombe wall[2]
It is a classic Trombe wall but in which the gap between the Trombe wall and glazin
g is fill with a highly absorbent, low-density fluid[2].
Fan forces the air through the fluidized bed there by Facilitating effective heat
transfer.
Two filters, which are located at the top and bottom of the air channel, prevent the
fluidized particles from entering the room[7].
This system has effective heat transfer due to direct contact between air and fluid
particles [8] since the surface area is increased compared to wall in the conventional
Trombe wall.

6. Phase Change Material Trombe wall
 The PCM absorbs the solar energy and changes its phase there by storing heat(latent) energy
, which can be released by reversing phase change in night times.
 Commonly used PCM’s are phase eutectic salts( NaCl , potassium nitrate) or salt hydrates
(Calcium chloride, Sodium sulphate) and paraffin wax[2].
Paraffin wax: Most widely used PCM
 Cheap with moderate thermal storage densities (200 kJ/kg or 150 MJ/𝑚3) and
a wide range of melting temperatures.
 However, they have low thermal conductivity (0.2 W/ 𝑚 𝑜C), which limits thei
r applications. Metallic fillers, metal matrix structures, finned tubes and alumi
num shavings were used to improve their thermal conductivity.

7. Phase Change Material Trombe wall

8. Trombe Wall with PCM (cndt.)
Advantages:
 These PCM’s store more energy in a smaller volume and in materials those are lighter than n
ormal building materials there by reducing size and weight of storage medium.
 A 15 cm concrete wall can be replaced by a 3.5 cm wall of PCM and perform similarly[3].
 The time of energy release can be altered by altering the initiation given for phase change at
night times.
Disadvantages :
 Performance of PCM is strongly dependent on thermal stability, repetitive cycling, corrosion
between PCM and container[4] (concrete wall).
 Salts have high thermal stability but often suffers from high corrosion, Paraffin wax provides
a good option as paraffin's have excellent thermal stability as neither the cycles nor contact w
ith metals degrades their thermal behavior[5].
 Reactivity of PCM can be decreased by encapsulating it by non reactive materials like high d
ensity polyethylene sheets or plastic pipes[6].

9. Composite Trombe Wall
 Also called as Trombe-Michel wall, consists of: Semi transparent cover, a mass
heating wall, a closed cavity,
a ventilated air cavity and an insulating panel.
 Composite Trombe walls are considered a remedy[11] for two deficiencies of
Trombe walls:
 Heat loss during cloudy winter days and
 Undesired heat inputs during hot weather
 Both these effects were due to insulation on inner wall
surface.
 Unlike the conventional Trombe walls percentage of heat
Transferred through conduction or radiation is very less due
To the presence of insulation on inner side of wall.

10. Composite Trombe Wall

11. Composite Trombe Wall (cndt.)
Advantages:
 Users can control the rate of heating by controlling the airflow through the
ventilated channel.
 The composite Trombe wall’s thermal resistance is extremely high because the
wall is insulated on the inner side.
Disadvantages:
 This type of wall requires a mechanism to prevent reverse thermo-circulation,
which occurs when the storage wall becomes colder than the ambient air of the
building’s internal space.
The reverse thermo-circulation can be avoided by using plastic film insertion in the
vents which allows the flow of air only in one direction[11].

12. Composite Trombe Wall (cndt.)

13. BIPV Trombe Wall
Building integrated photovoltaic thermal (BIPV/T) systems are either opaque or se
mi-transparent type PV on roof top or facade.
Principle:
The system removes the heat behind the PV panels and cools them.
The decrease in the PV surface temperature provides the increase in electrical effici
ency.
The air heated in the air duct/gap is heated up and taken into the building’s HVAC s
ystem.
The use of pre-heated air in the HVAC system provides the decrease in the heating
and the ventilation loads.
Application:
Production and availability of semi transparent PV modules makes it viable for Tra
ns wall systems also, while opaque PV modules are limited to trombe wall only.

14. BIPV Trombe Wall
CONCLUSIONS:
 The experiments conducted using a-Si BIPV/T has given an Increase of 2% [9]
electrical efficiency and temperature difference out door and outlet air is 16.89 𝑜
C
thermal performance is reduced by 17%[10].
 Double glazing thermal walls are also getting popular, This will have less heat
loss during night times due to increased Thermal resistance . but reduction of
transmittance is a problem.
 In single glass system the solar gain during day time is more due to more transitivity
compared to double glass.
 Thus single glass system with shutters in the night is better than double glass system.

15. References
1) NREL. Building a better Trombe wall, NREL researchers improve passive
solar technology. National Renewable Energy Laboratory; 2005.
2) K. Sopian, C.H. Lim, Nilofar Asim, M.Y. Sulaiman , Trombe walls: A revi
ew of opportunities and challenges in research and development, Omidrez
a Saadatian n, Renewable and Sustainable Energy Reviews 16 (2012) 634
0–6351
3) Bourdeau LE. Study of two passive solar systems containing phase chang
e materials for thermal storage. Fifth Natl passive solar conference. Amhe
rst, Mass: Smithsonian Astrophysical Observatory; 1980.
4) Zalba B, Marin J, Cabeza L, Mehling H. Review on thermal energy storag
e with phase change: materials, heat transfer analysis and applications. Ap
pl Therm Eng 2003;23:251–83.
5) Gibbs B, Hasnain S. DSC study of technical grade phase change heat stor
age materials for solar heating applications. In: Proceedings of the 1995 A
SME/JSME/JSEJ International Solar Energy Conference, Part 2, 1995.
6) Hong Y, Xin-shi G. Preparation of polyethylene–paraffin compounds as a
form-stable solid–liquid phase change material. Solar Energy Mater Solar
Sells 2000;64:37–44.

16. References
7) Sadineni SB, Madala S, Boehm RF. Passive building energy savings: a r
eview of building envelope components. Renewable and Sustainable En
ergy Reviews 2011;15:3617–31.
8) Tunc M, Uysal M. Passive solar heating of buildings using a fluidized be
d plus Trombe wall system. Applied Energy 1991;38:199–213.
9) Panels , Basak Kundakci Koyunbaba Zerrin Yilmaz b, The comparison
of Trombe wall systems with single glass, double glass and PV
10) Sun W, Ji J, Luo C, He W. Performance of PV-Trombe wall in winter cor
related with south facade design. Applied Energy 2011;88:224–31.
11) Zalewski L, Chantant M, Lassue S, Duthoit B. Experimental thermal stu
dy of a solar wall of composite type. Energy and Buildings 1997