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  • nhkim1809
    • Jun 21, 2021
    • 7 min read

<EnergiON_PCM Microcapsule> GE Material Report by ACTIVON GE Lab Vol.01


1. What is Phase Change Material (PCM)?

PCM is a material that can store energy and spontaneously store or emit heat in the form of latent heat while maintaining the temperature when its phase changes from solid to liquid or from liquid to solid according to changes in ambient temperature.

Suppose a solid PCM changes its phase at 28℃. When heated from a temperature lower than 28°C, it becomes liquid as its temperature is higher than 28°C by absorbing the heat. On the other hand, when the liquid PCM is cooled to lower than 28℃, it emits the heat within it to become solid.

Figure 1. Principles of PCM

Why Phase Change Material (PCM)?

Excessive use of fossil fuels has given rise to a variety of problems including global warming, ozone depletion, and environmental pollution. There have been efforts to find methods of solving the problems and alternatives. Excessive use of fossil fuels has also increased the emission of greenhouse gases on an annual basis, with the amount of greenhouse gas emitted by the energy industry accounting for 86.9%, thereby serving as the main source of greenhouse gas emission. One of the alternatives to reduce greenhouse gases is the development of eco-friendly energy. Recently, thermal energy storage technology using phase change materials (PCMs) has been developed, and these are materials that have been applied to various types of technology.

Table 1. Annual Greenhouse Gas Emissions
Figure 2. Headlines related to PCM technologies

Classification and Features of PCM

PCMs can be roughly divided into organic PCMs and inorganic PCMs. Organic PCMs include paraffins, fatty acids, sugar alcohol, etc.

Table 2. Classification and Features of PCM

Research of PCM

<Heat Storage Technology with PCM> Institute for Advanced Engineering_Energy Environment Research Team, 2018

It is possible to store heat in the form of latent heat by recovering waste heat generated from industrial facilities and power generators and using PCMs’ property of storing heat. The technology requires facilities including heat storage facilities for storing heat, greenhouses of growing crops with the stored heat, facilities to supply hot water and heating to public convenience facilities such as swimming pools and campsites, facilities to control industrial processes such as heat transfer media of heat storage systems, and facilities for cars delivering the heat as a form of courier.

The core technologies include the CFD analysis of the physical properties and phase changing of PCMs as heat storage materials, design of storage tanks within which the temperature and melting points of PCMs are controlled and the fluidity of the heat transfer materials is uniformly maintained, and design and operation of systems for storing and emitting heat.

A 4GJ-class PCM heat storage system was installed in Geochang, Korea, and its test operation was completed. We plan to promote a project of recovering waste heat and improving efficiency in using waste heat.

Figure 3. A system that recovers waste heat and uses the thermal storage energy for industry and agriculture

<Safe and efficient hot water supply using PCM capsules> Korea Institute of Science and Technology (KIST), 2019

The hot water for heating houses is about 50℃. Korea District Heating Corporation delivers high-temperature water (over 110℃) through high-pressure pipes because of the large heat loss in the process of supplying. When the hot water over 110°C passes, the pipes may rupture. To compensate for this problem, we developed a technology wherein PCMs are encapsulated in the shape of oval beads and delivered through the pipes. The PCM capsules are maintained at about 50℃ during its phase change from solid to liquid, storing more than 70 times more heat than general water at the same temperature. When the PCM capsules are in the pipes, only 50℃ is enough for the hot water instead of 110℃, considerably reducing heat loss and preventing rupture of the pipes. In addition, the PCM capsules can be used semi-permanently, providing environmental and economic advantages.

Figure 4. Schematic diagram displaying the 4th-generation thermal energy network using PCM transport
Figure 5. Hot Water Transport Using PCMs

<Development and Application of PCM Cool Roof System Technology for the Reduction of Urban Heat Island Phenomenon> Chungang University’s Industry-University Cooperation Foundation (July 2014 to July 2017)>

This study aimed to develop a plate-type “PCM Cool Roof System” for application to building roofs and to reduce the urban heat island phenomenon and cooling load, resulting in a decrease in greenhouse gases. We designed a PCM plate, applied it to scale modeling and mock-up modeling on-site, and measured the thermal data loggers and heat flow to verify the performance of the “PCM Cool Roof System.” Since there have been no methods or standards to design a building roof applied with PCMs, we plan to promote the distribution and dissemination of design standards from the technology we developed.

Figure 6. Cool Roof System applied with PCMs

Current use of PCM

1) NASA

- NASA applied PCMs to develop next-generation spacesuits to protect astronauts from harsh changes in extraterrestrial temperature. Currently, the technology is used to manufacture clothing used in daily life such as shirts, T-shirts, and underwear as well as blankets and sheets.

Figure 7. A spacesuit with PCMs

- NASA has also developed “PCM-HX,” a heat exchanger equipped with PCMs. The PCMs in PCM-HX absorb the extraterrestrial heat to become liquid; when the heat is emitted through the radiator inside the spaceship, PCMs are cooled to become solid. The emitted heat is again absorbed by PCM-HX, resulting in thermal circulation. NASA is planning to verify the performance of PCM-HX within the “Orion Spaceship” in cooperation with the International Space Station (ISS).

Figure 8. PCM-HX

2) <Market for Cold Chain>

- The “Cold Chain” market has been expanding with the recent spread of contactless consumption. Cold Chain refers to low-temperature distribution systems that maintain a low temperature throughout the entire distribution process (production, storage, distribution, and sale) to protect the quality of fresh food and medicines from the fluctuation of temperature. Ice packs, dry ice, and expanded polystyrene and Styrofoam have been used for low-temperature distribution, but they cannot maintain the low temperature for a long time.

PCMs can be an alternative to overcome the disadvantage. By applying PCMs’ ability to maintain a constant temperature to the Cold Chain market, it is possible for the distributors to maintain a low temperature for a long time for their products. In addition, PCMs have other advantages, i.e., they can be used permanently based on the storage state, and a wide range of temperature can be maintained according to their types.

Figure 9. PCM transport boxes and ice packs
Figure 10. Structure of a refrigerator truck with PCMs

3) <Energy Saving in Buildings and Data Centers>

- A data center refers to a facility that collects various data, operating servers numbering hundreds to tens of thousands at the same time. One of the biggest concerns for data centers is energy saving, because a lot of energy is being consumed to operate data centers owing to the heavy increase in data. Thus, data centers require various ideas and technologies to save energy. The “Phase Change Solution” used PCMs to save energy. In the solution, a panel filled with PCMs is attached to the inside of a structure to absorb and emit the heat from the electronic devices inside the structure, optimizing its thermal performance. The panel enables the HVAC equipment to cool the devices properly by reducing overload, thereby improving the stability and performance of the electronic devices.

l Data Center: A facility where computer systems, communications equipment, and storage devices are installed. It serves as a core infrastructure that stores and distributes big data, requiring enormous power.

l HVAC: Heating, ventilation, and air conditioning encompass technologies for comfortable indoor or car environments.

Figure 11. Use of PCM panels for energy saving

Conclusion

The 2030 Nationally Determined Contribution establishes a goal requiring 100 countries to reduce their greenhouse gas emission by 24.4% by 2030 compared to 2017. In order to achieve the goal, it seems inevitable to reduce energy production from fossil fuels; thus, the market values of energy sources that can replace fossil fuels are expected to increase.

As an energy source to replace fossil fuels, PCMs have increased their market size annually, but the domestic market for them is remarkably smaller than overseas markets. Currently, most of the PCMs in Korea are imported for distribution. There have been few domestic cases wherein PCMs are developed for application; hence the need for more investment in expanding the domestic market and developing technologies related to PCMs.

As indicated by the current national policies, the trend of being eco-friendly and renewable has been spreading. The manufacture of PCMs is going to be affected by such trend; bio-based refined PCMs are expected to have higher growth potential in the market than inorganic PCMs or those refined from petroleum.

One of the reasons PCMs are rarely applied to various industries is their high price. When the price drops with the technologies related to refining PCMs, however, such can contribute to expanding the use of PCMs.




References

- Chungang University’s Industry-University Cooperation Foundation, “Development and Application of PCM Cool Roof System Technology for the Reduction of Urban Heat Island Phenomenon” (July 2014 to July 2017)

- Soongsil University’s Industry-University Cooperation Foundation, “Plans for the Development and Application of PCM to Buildings to Improve Performance of Residential Area” (September 7, 2016 to March 6, 2017)

- Ministry of Environment, Korea Environmental Industry and Technology Institute, “Trends of Thermal Energy Storage Technology Using PCMs”

- Ministry of Environment (Greenhouse Gas Inventory and Research Center), “Inventories of National Greenhouse Gases (1990 - 2018)”

- Institute for Advanced Engineering (Energy Environment Research Team), “PCM Heat Storage Technology” (2018)

- Korea Institute of Science and Technology (KIST), “Safe and efficient hot water supply using PCM capsules” (2019)

(https://www.kist.re.kr/kist_web/?sub_num=2935&ord=0&pageNo=1&state=view&idx=2606)

- NASA’s website

(https://www.nasa.gov)

- Website of Phase Change Solutions (https://phasechange.com)

- Energy Solution Technology (EST)’s website (www.est-in.com)

- OCI’s website (https://www.oci.co.kr)

- BINGO ICE website (https://bingoice.com)


Image credits

- Table 1. Annual Greenhouse Gas Emissions

- → <Ministry of Environment (Greenhouse Gas Inventory and Research Center), “Inventories of National Greenhouse Gases> (1990 - 2018)” (Excerpt)

- Figure 2. Headlines related to PCM technologies

- → ① EST’s “cooling storage system”… for pharmaceutical and food products

- ② KIST develops a building wall material that lowers indoor temperature by 2.5 degrees

- ③ OCI expands its “cold chain” market business… ”2x better at maintaining temperature”

- Figure 3. A system that recovers waste heat and uses the thermal storage energy for industry and agriculture

- Figure 4. Schematic diagram displaying the 4th-generation thermal energy network using PCM transport

- Figure 5. Hot Water Transport Using PCMs

- Figure 6. A Cool Roof System with PCMs

- Excerpt from <Chungang University’s Industry-University Cooperation Foundation, ”Development and Application of PCM Cool Roof System Technology for the Reduction of Urban Heat Island Phenomenon” (July 2014 to July 2017)>

- Figure 7. A spacesuit with PCMs (NASA)

- Figure 8. PCM-HX (NASA)

- Figure 9. Transport boxes and ice packs made of PCMs

- Figure 10. A refrigerator truck with PCMs

- Figure 11. Use of PCM panels for energy saving

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