12 Direct Photo-Thermal Energy Storage Using Nanoparticles …
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outlet of solar thermal system and circulating it in a pipe through the PCM containing storage tank. Herein, the heat of the fluid gets transferred to the PCM primarily
through conduction and therefore the pipe material is invariable a highly conducting
material (such as copper). Furthermore, researchers have used pipes with fins and
employed various agitation techniques to enhance the heat transfer. Recently, the
photon-transport based optical charging (OC) wherein, the solar irradiance directly
interacts with the PCM has proven to significantly improve the charging process.
Herein, nanoparticles have been seeded in the conventional PCMs to enhance its
absorption capability; and the nanoparticle-laden PCM directly interacts with the
incident sunlight through absorption and scattering mechanisms. Although, seeding
nanoparticles into a transparent PCM is the most effective proposition but researchers
have revealed that photon-transport based optical charging can still be applicable to
nanoparticles-laden opaque PCMs (Wang et al. 2017). To enhance the charging rate
researchers have dispersed various nanoparticles in PCMs (Cu NPs, Au NPs, Al 2 O 3
NPs, metal foam copper, carbon nanotubes sponge, hybrid NPs etc.)—these could
be broadly classified into plasmonic metallic nanoparticles or carbon-based broad
absorption nanoparticles.
With the objective of optimizing the optical charging process, there have been
efforts to understand the photon-nanoparticle laden PCM interaction mechanism
and subsequently the melting process. Richardson et al., studied the light interaction
with gold nanoparticles dispersed in ice matrix (Richardson et al. 2006). Chen et al.,
enhanced the enthalpy and thermal conductivity of PCM through usage of deformable
carbon nano-tube sponge wherein energy storage is driven by illumination (Chen
et al. 2012). Lin and Al-Kayiem used copper NPs to improve the thermophysical
properties of PCMs for thermal energy storage (Lin and Al-Kayiem 2012). Usage
of copper NPs in solar pond has been proven to reduce the charging and discharging
time significantly (Karunamurthy et al. 2012). Alumina NPs dispersed into PCM to
form a nano-PCM which has been used to increase the charging rate as compare to
pure PCM (Pise et al. 2013). Hybrid nanoparticles have been used in solar heating
systems to enhance the storage and nanofillers of graphene NPs have been found
to enhance the thermal conductivity with increase in loading of NPs (Harikrishnan
et al. 2014; Fan et al. 2013). Ultra-thin foam dispersed into PCM have shown to
significantly increase the thermal conductivity at even low volume fractions (up to
18 times) and PCM filled spherical capsules have also been used to increase the
thermal storage, cyclohexane with copper nanoparticles have been dispersed into
PCM with porous medium to increase the energy storage (Ji et al. 2014; Khot et al.
2012; Hossain et al. 2015). The addition of metal foams has shown to increase the
overall heat transfer up to 3–10 times. Researchers have also shown that usage of
liquid metal gallium as nano-PCM reduces the melting time and improves thermal
storage (Zhao et al. 2010; Wang et al. 2014; Alomair et al. 2017; Salyan and Suresh
2018).
The present work is essentially an attempt to further understand the optical charging and discharging process. This shall help in identifying the key parameters and
processes impacting the melting rate of nanoparticle-laden PCMs. Firstly, we prepare
the samples of nano PCM by using ultra-sonication method. Two set of experimental
237
outlet of solar thermal system and circulating it in a pipe through the PCM containing storage tank. Herein, the heat of the fluid gets transferred to the PCM primarily
through conduction and therefore the pipe material is invariable a highly conducting
material (such as copper). Furthermore, researchers have used pipes with fins and
employed various agitation techniques to enhance the heat transfer. Recently, the
photon-transport based optical charging (OC) wherein, the solar irradiance directly
interacts with the PCM has proven to significantly improve the charging process.
Herein, nanoparticles have been seeded in the conventional PCMs to enhance its
absorption capability; and the nanoparticle-laden PCM directly interacts with the
incident sunlight through absorption and scattering mechanisms. Although, seeding
nanoparticles into a transparent PCM is the most effective proposition but researchers
have revealed that photon-transport based optical charging can still be applicable to
nanoparticles-laden opaque PCMs (Wang et al. 2017). To enhance the charging rate
researchers have dispersed various nanoparticles in PCMs (Cu NPs, Au NPs, Al 2 O 3
NPs, metal foam copper, carbon nanotubes sponge, hybrid NPs etc.)—these could
be broadly classified into plasmonic metallic nanoparticles or carbon-based broad
absorption nanoparticles.
With the objective of optimizing the optical charging process, there have been
efforts to understand the photon-nanoparticle laden PCM interaction mechanism
and subsequently the melting process. Richardson et al., studied the light interaction
with gold nanoparticles dispersed in ice matrix (Richardson et al. 2006). Chen et al.,
enhanced the enthalpy and thermal conductivity of PCM through usage of deformable
carbon nano-tube sponge wherein energy storage is driven by illumination (Chen
et al. 2012). Lin and Al-Kayiem used copper NPs to improve the thermophysical
properties of PCMs for thermal energy storage (Lin and Al-Kayiem 2012). Usage
of copper NPs in solar pond has been proven to reduce the charging and discharging
time significantly (Karunamurthy et al. 2012). Alumina NPs dispersed into PCM to
form a nano-PCM which has been used to increase the charging rate as compare to
pure PCM (Pise et al. 2013). Hybrid nanoparticles have been used in solar heating
systems to enhance the storage and nanofillers of graphene NPs have been found
to enhance the thermal conductivity with increase in loading of NPs (Harikrishnan
et al. 2014; Fan et al. 2013). Ultra-thin foam dispersed into PCM have shown to
significantly increase the thermal conductivity at even low volume fractions (up to
18 times) and PCM filled spherical capsules have also been used to increase the
thermal storage, cyclohexane with copper nanoparticles have been dispersed into
PCM with porous medium to increase the energy storage (Ji et al. 2014; Khot et al.
2012; Hossain et al. 2015). The addition of metal foams has shown to increase the
overall heat transfer up to 3–10 times. Researchers have also shown that usage of
liquid metal gallium as nano-PCM reduces the melting time and improves thermal
storage (Zhao et al. 2010; Wang et al. 2014; Alomair et al. 2017; Salyan and Suresh
2018).
The present work is essentially an attempt to further understand the optical charging and discharging process. This shall help in identifying the key parameters and
processes impacting the melting rate of nanoparticle-laden PCMs. Firstly, we prepare
the samples of nano PCM by using ultra-sonication method. Two set of experimental