258
R. Saxena et al.
For integrating PCMs into any building, five methods have been suggested, they are,
direct incorporation, immersion, vacuum impregnation, encapsulation, shape and
form stabilized materials (Navarro et al. 2016a; b).
13.4.1 Direct Incorporation
It deals with adding PCM directly to the building material such as concrete etc. Feldman et al. carried out direct incorporation of butyl stearate by 22% in the gypsum.
The energy storage capacity was reported to have increased by ten-fold times (Feldman et al. 1991). However, there can be leaking problems as reported by Soares et al.
(2013). Direct incorporation in concrete is still a topic of research as there are two
major challenges first is that PCMs undergo phase change thus, they often leak or
separate out from the mixture. Second, they readily do not mix with concrete and separate out which is to be taken care of, while mixing. Thus, other techniques/methods
are used for PCM mixing.
13.4.2 Immersion
In this method, the construction elements are soaked or dipped in the container filled
with PCM, which thus gets absorbed within the construction material. Immersion
method requires many hours of soaking (Ling and Poon 2013). This method however
is often not used due to leakage problems (Soares et al. 2013) and due to compatibility
issues with certain building materials (Hawes et al. 1989). This method however, is
slightly different from direct incorporation however, it faces similar constraints and
problems in case of PCMs.
13.4.3 Vacuum Impregnation
In this method the air is first evacuated using the vacuum pump and soaked in the
PCM container thereby replacing the air in the pores by the PCM. There is an effective
reduction in the overall thermal conductivity of the sample. This method is generally suitable in case of foams etc. where thermal conductivity is to be reduced for
insulation purpose. This method however has similar shortcomings for solid-liquid
PCMs as previous cases.
R. Saxena et al.
For integrating PCMs into any building, five methods have been suggested, they are,
direct incorporation, immersion, vacuum impregnation, encapsulation, shape and
form stabilized materials (Navarro et al. 2016a; b).
13.4.1 Direct Incorporation
It deals with adding PCM directly to the building material such as concrete etc. Feldman et al. carried out direct incorporation of butyl stearate by 22% in the gypsum.
The energy storage capacity was reported to have increased by ten-fold times (Feldman et al. 1991). However, there can be leaking problems as reported by Soares et al.
(2013). Direct incorporation in concrete is still a topic of research as there are two
major challenges first is that PCMs undergo phase change thus, they often leak or
separate out from the mixture. Second, they readily do not mix with concrete and separate out which is to be taken care of, while mixing. Thus, other techniques/methods
are used for PCM mixing.
13.4.2 Immersion
In this method, the construction elements are soaked or dipped in the container filled
with PCM, which thus gets absorbed within the construction material. Immersion
method requires many hours of soaking (Ling and Poon 2013). This method however
is often not used due to leakage problems (Soares et al. 2013) and due to compatibility
issues with certain building materials (Hawes et al. 1989). This method however, is
slightly different from direct incorporation however, it faces similar constraints and
problems in case of PCMs.
13.4.3 Vacuum Impregnation
In this method the air is first evacuated using the vacuum pump and soaked in the
PCM container thereby replacing the air in the pores by the PCM. There is an effective
reduction in the overall thermal conductivity of the sample. This method is generally suitable in case of foams etc. where thermal conductivity is to be reduced for
insulation purpose. This method however has similar shortcomings for solid-liquid
PCMs as previous cases.