Phase Change Materials as an environmental approach for cold storage

Phase Change Materials as an environmental approach for cold storage

Ertugral Güngör, T., Journal of Global Climate Change

Today, nearly half of food products are decreasing before reaching to consumer and data shows that one third of food never reaches to end consumer. It is known that % 50 of these are caused by technical errors, temperature management and reducing postharvest losses will play important role of world population in future.

Therefore, preventing or minimizing loss of fresh fruits and vegetables has be-come important issue.

Petroleum fuels and electrical energy cold storages are costly and causes envi-ronmental pollution.

Recently, phase change material (PCM) is clean, environmentally friendly and renewable energy source and interesting material in energy systems.

PCMs have ability to store ambient heat as latent heat energy and return the stored latent heat energy during rising and falling to ambient temperature.

Accurate phase change temperature range PCMs work as low and high temperature barriers, providing maximum energy savings as an economical storage system and can prevent carbon (C) emissions by reducing environmental pollution.

This study is a review of applicable thermal energy storage PCM materials for cold storage of postharvest fresh fruits and vegetables and aims to reduce to emission and energy saving.

PCMs role in energy in energy use and its impact on C emissions
Heat energy can be stored as sensible, latent and thermochemical energy.

Latent heat storage is most interesting method. PCMs are substances that can absorb and store heat during the phase change process and dissipate this stored heat in case of reverse phase change (Tao et al., 2008; Boan, 2005).

The phase change is basically caused by temperature change caused by heat source coming from stable state of substance.

In latent heat storage technique, PCMs have energy storage/release function during phase change at specified temperature.

PCMs have an important place with high energy storage, isothermality and controlled phase change (Zalba et al., 2003; Kenisarin and Mahkamov, 2007).

Many organic and inorganic PCMs and their mixtures (Fig.1) are used in solar heating (water, building etc.) and temperature regulation in textiles, thermal management of electronics, biomedical and biological transport systems, etc.

PCMs have high impact strength and chemical resistance (Alkan et al., 2006). PCMs are nowadays used in solar energy storage, heat pumps, heating and air conditioning in buildings, heat distribution systems, etc. widely used in the fields.

Studies on PCM microcapsules have increased in the last 10 years (Gulfam et al., 2020).

Preparation of new generation materials with modified PCM studies, for example, a new PCM was synthesized by connecting polyethylene terephthalate to polyethylene glycol (Gungor Ertugral and Alkan, 2021).

In solid-liquid phase change, food packaging containing PCM in solid state can minimize temperature fluctations that can occur foodstuff (Johnston et al., 2008) also provides insulation by preventing changing ambient temperature from reaching food for a long time.

Organic and inorganic PCMs have been tried by many researchers to elicit maximum thermal efficiency available (Sathishkumar et al., 2020). PCM system was used to home refrigerator and compressor worked 3,566 hours a day and operating time was reduced by 45 minutes compared to previous year and it was observed that carbon dioxide emissions were reduced by % 17.4 and fossil fuel consumption by 28 kg and 12 liters per day, respectively (Zara- jabad and Ahmadi, 2018).

It is possible to preserve quality and safe food by using as little energy sources as possible. For this purpose, the interest in environmentally friendly, new generation, smart packaging materials that can keep food cold for a certain period time, which is beneficial to the global economy as parallel.

Applicable PCMs to cold storage of postharvest fruits and vegetables
Appropriate PCM selection is save energy for cold chain during storage and transportation of foods.

Preservation of storage temperature in range of 8-10 °C suitalbe to ripe tomatoes and it is also best storage temperature range for potatoes, citrus fruits, star fruit, melon, okra, pineapple and zucchini (Cantwell, 2001).

Various PCMs can be used as packaging material to keep temperature constant by using minimum external energy source in cold chain applications of postharvest fruits and vegetables whose stor-age temperatures vary between 5-18°C (Table 3).

It has been observed that a PCM plate integrated in a vertical structure reduces energy consumption by about 10 times, when plate thickness increases by 6 mm, the compressor run time ratio decreased from % 36 to % 26 (Ezan et al., 2017) and Rubitherm brand PCMs used in storage box- es for cold chain applications that have been effective in cooling (Du et al., 2020).

Table 3 of the original paper list the PCMs applicable for the postharvest preservation of fruits and vegetables. References are also available in the original paper.

Picture is Fig. 1 of the original paper, Classification of PCMs (Tatsidjodoung et al., 2013)

Review of phase change materials as an environmental approach for postharvest fruit and vegetable cold storage
Ertugral Güngör, T., Review of phase change materials as an environmental approach for postharvest fruit and vegetable cold storage. Journal of Global Climate Change. 2022; 1(1): 21-32,DOI: 10.56768/jytp.1.1.04