Hydrogen has been identified to play a
key role as an energy source in the future. It has the highest
energy content per unit mass of any known fuel. When burned in an
engine, hydrogen produces effectively zero emission; when powering a
fuel cell, its only waste is water. However, significant
technological challenges exist towards reducing its cost and storage
volume and assuring its safety. Among the storage techniques being
developed, cryogenic liquid storage of hydrogen is preferred because
of relatively lower storage volume and the ease of regeneration of
the fuel with variable demand. However, hydrogen losses due to
boil-off because of the heat leak from the ambient into the storage
tank is a concern. The Zero Boil-Off (ZBO) concept is employed for
tackling the situation with a balanced heat removal and forced
mixing. The study considered a cylindrical tank with elliptical top
and bottom as shown in the figure. The tank wall is made of aluminum
and a multi-layered blanket of cryogenic insulation (MLI) has been
attached on the top of the aluminum. The tank is connected to a
cryocooler via a heat pipe to dissipate the heat leak through the
insulation and tank wall into the fluid within the tank. The
condenser section of the heat pipe dissipates heat to the cryocooler
while the evaporator section picks up heat from the fluid within the
tank. The hot fluid is directed to the heat pipe using a fluid
circulation system within the tank. This system consists of a pump,
a spray head for discharge of fluid and a collector tube network
feeding to the pump. Different heat pipe sizes, different locations
of hot fluid collection and discharge, and different discharge
velocities are being investigated.
demand. However, hydrogen losses due to
boil-off because of the heat leak from the ambient into the storage
tank is a concern. The Zero Boil-Off (ZBO) concept is employed for
tackling the situation with a balanced heat removal and forced
mixing. The study considered a cylindrical tank with elliptical top
and bottom as shown in the figure. The tank wall is made of aluminum
and a multi-layered blanket of cryogenic insulation (MLI) has been
attached on the top of the aluminum. The tank is connected to a
cryocooler via a heat pipe to dissipate the heat leak through the
insulation and tank wall into the fluid within the tank. The
condenser section of the heat pipe dissipates heat to the cryocooler
while the evaporator section picks up heat from the fluid within the
tank. The hot fluid is directed to the heat pipe using a fluid
circulation system within the tank. This system consists of a pump,
a spray head for discharge of fluid and a collector tube network
feeding to the pump. Different heat pipe sizes, different locations
of hot fluid collection and discharge, and different discharge
velocities are being investigated.