Thermal Energy Storage
Introduction To TESS
Latent Heat Storage
Phase change materials and application
Case study application
Thermal energy storage –Why do we need it ?
Energy demands vary on daily, weekly and seasonal bases. TES is helpful for balancing
between the supply and demand of energy
Thermal energy storage (TES) is defined as the temporary holding of thermal energy in
the form of hot or cold substances for later utilization.
TES systems deal with the storage of energy by cooling, heating, melting, solidifying or
vaporizing a material and the thermal energy becomes available when the process is
TES system for a particular application depends on storage duration, economics, supply
and utilization temperature requirements, storage capacity, heat losses and available
TES : Thermal Energy Storage
0 5 10 15 20 25
Heat added Q
Process flow in a TES
Charging Storing DischargingExcess
Thermal Energy Storage types
LHES and SHES
Sensible Heat Storage
Thermal energy is stored by raising the temperature of a solid orliquid. SHS
system utilizes the heat capacity and the change in temperature of the material
during the process of charging and discharging.
Amount of heat stored depends on the specific heat of the medium, the
temperature change and the amount of storage material.
Ti = Initial Temperature
Tf= Final Temperature
Q= Heat stored Cp =Specific Heat m= mass of the material
The earliest Latent Heat energy storage system
Selection Criteria for PCM material
latent and sensible heat capacities
Thermal stability, mechanical stability
Cyclic property degradation
Heat transfer characteristics
Ozone depleting potential
Ease of encapsulation
Melting Enthalpy and Temperature of PCM materials
Melting temperatures help in
choosing the correct material
for an application
Organic PCM materials
Paraffins, fatty acids and sugar alcohols can be used as PCM . These material classes cover the
temperature range between 0 ºC and about 200 ºC.
Due to the covalent bonds in organic materials, most of them are not stable to higher
The most commonly used organic PCM are paraffins. Paraffin is a technical name for an
alkane, but often it is specifically used for linear alkanes with the general formula CnH2n+2
Paraffins show good storage density with respect to mass, and melt and solidify congruently
with little or no subcooling.
Thermal conductivity is comparatively low.
vapor pressure is usually not significant. Their volume increase upon melting is in the order of
10 vol.%; this is similar to that of many inorganic materials, but less critical as paraffins are
softer and therefore build up smaller forces upon expansion.
Alkanes as PCM materials
-Pure Alkanes are
-A mixture of alkanes
can be used
-This provides better
flexibility in terms of
A3 Author, 9/2/2015
A4 Tetra Decane is the smallest alkane which has a melting point higher than zero
Technical Data for a RT-25 , Rubitherm GMBH
Commercially Available Phase change material
Solar thermal-Single tank schematic
Solar thermal -Two tank molten salt storage
• PCM materials are used for stabilizing temperatures during
transportation of goods
• They have replaced water as the temperature stabilization agent
in medicine transportation. Due to the fact that PCM’s have higher
melting point then water the medicine will not be subjected to
lower temperatures then necessary and the risk of crystallization
in the product has been eliminated.
• PCM can revolutionize the frozen goods transportation market.
• Replaced Dry ice is the most common used freeze agent in this
type of transportations today. It is
PCM performance in cold chain application
Generic Name Pros (Cold chain application) Cons(Cold chain application)
n-Alkanes: CH3(CH2)nCH3 High latent heat; inert,
non-toxic, non- corrosive
Fatty Acid Methyl Esters:
Biodegradable, non-toxic, non-
Limited availability, strong odor,
solvent for EPS, latent heat
Biodegradable, non-toxic Limited availability, odor,
flammable, easily oxidized,
latent heat below alkanes
Fatty Acids: CH3(CH2)nCOOH Biodegradable, good cycling
stability, limited super-cooling
Limited availability, causes
burns, corrosive, latent heat
Water based systems, packaging
compatible, good latent heat
Very limited availability, poor
cycling stability, may be
PCM materials are used for creating temperature
control in Green buildings.
• Commercial projects in Australia and Canada are
showing good performance .
• Encapsulated PCM materials can be mixed with
the building construction material according to the
• Lot of research is being done on embedding PCM
material in the glasses used in buildings these days
• Both cold and hot climates can benefit from the
use of PCM in building applications .
• Increases the “thermal inertia” of the buildings by
• Organic PCM materials are being used
Case studies and application
Type Category 1
Type Category 2
Rated Power in
Status Web Link
India One Solar
Major companies in India
CoolElectrica- Promthean Power systems
Pluss (Research , Development and Manufacturing)
TESSOL Launches PLUGnCHILL Freezebox for grocery e-
TESSOL has developed a single and dual temperature freezer
box for chilled and frozen transport of food / pharma products
in the last mile. The box that comes in 100-200 liter capacity
can transport goods in a desired temperature range for 6-8
hours while maintaining the desired temperatures. Some key
features of the system:
1. Compressor less system on board (no power connection or
additional load required)
2. Contains chargeable cartridges that can be added and
removed in a couple of minutes
3. Thermal cartridges charged in an outside chiller and inserted
in the vehicle 30 mins before leaving for a delivery
Freezebox Fits inside the delivery
Promethean Power Systems
Produce at the
• First cool and then transport principle enables longer
shelf life and higher margins on premium quality
• Capture more % of farmers in the catchment area.
• Eliminates post harvest losses
Cold storage back
• Eliminates Diesel generator sets.
• Low maintenance and operation costs.
• Unlike electro-chemical batteries , thermal batteries
don’t require replacement every 3-5 years.
• Single phase connection at farms
• Easy to operate.
Challenges with Phase change materials
Material Properties and Thermal Performance
Packaging for Use
Conditioning for Use
Cost and Availability
Health, Safety and Disposal
Comparison of water based and PCM based packaging
Thermo Chemical Energy Storage (Brief)
• Storage by means of chemical
• Using reversible
• Drawbacks may include
uncertainties in the
thermodynamic properties of the
reaction components and of the
reaction kinetics under a wide
range of operating conditions,
high cost, toxicity, and
For more comprehensive lists of materials the reader should look at the early publications of Steiner et al. 1980, Abhat 1983, Lane 1983 and 1986,
Schröder 1985, and more recent publications like Kakiuchi et al. 1998, Hiebler and Mehling 2001, Zalba et al. 2003, Sharma et al. 2004, Farid et al.
2004, and Kenisarin andMahkamov 2007.