Applications with PCMs have endless possibilities and are gaining a large momentum in organizations to integrate it into their products. It has got a large potential to overcome the existing challenges offering new products for known application and new applications for known products. Industry has to step up and find innovative ways of using PCM!
1.As a dynamic thermal Insulation: Unlike conventional (sensible) storage materials, PCM absorbs and release heat at a nearly constant temperature. They store 5–14 times more heat per unit volume than sensible storage materials such as masonry, or rock. A large number of PCMs are known to melt with a heat of fusion in any required range (Atul Sharma, 2009). Phase change materials possess the ability to change their state with a certain temperature range. These materials absorb energy during the heating process as phase change takes place, otherwise this energy can be transferred to the environment in the phase change range during a reverse cooling process. The insulation effect reached by the PCM depends on temperature and time; it takes place only during the phase change (in the temperature range of the phase change) and terminates when the phase change in all of the PCMs would complete. Since, this type of thermal insulation is temporary; therefore, it can be referred to as dynamic thermal insulation.
2.As a back-up for cooling application: PCM can be used as a thermal battery which will offer un-interrupted cooling. For these applications, the PCM has to be integrated with the existing refrigeration system to ensure PCMs are fully charged by the refrigeration unit and is available instantaneously when there is a power outage. PCMs are widely used for building air-conditioning systems and for mission critical applications. Using PCMs are much lesser in cost as compared to diesel generators as PCMs get charged during off-peak hours when power is available. Another disadvantage of using diesel generators is the time lag to start the system which can be disastrous for mission critical applications.
In the retail or industrial freezers and coolers PCMs are integrated within the body of the machine such that the evaporator coil is in constant contact with the PCM. While the machine is plugged to the power, the refrigeration unit simultaneously charges the PCM and also keeps the cabin cool. The figure below illustrates the application of PCM in deep freezer. PCMs offer a backup of more than 16 hours protecting the product during power shutdowns.
In the cold chain application the reefer trucks consume a large amount of diesel for running the refrigeration unit and in many trucks there are also constraints in mounting a refrigeration unit. PCM integrated trucks offer the benefit of utilizing cheaper electric energy to store the thermal energy which will be sufficient to maintain the temperature for over 12 hours of transportation. This translates in to huge saving in the operational cost with a negligible impact on the capital cost.