Phase change material cellulosic composites for the cold storage of perishable products: From material preparation to computational evaluation Lucio Melone a , Lina Altomare a , Alberto Cigada a,b , Luigi De Nardo a,b,⇑ a Dipartimento di Chimica, Materiali e Ingegneria Chimica ‘‘Giulio Natta’’, Politecnico di Milano, Via Mancinelli 7, 20131 Milano, Italy b Local Unit, Istituto Nazionale di Scienza e Tecnologia dei Materiali, INSTM, Firenze, Italy article info Article history: Received 26 May 2011 Received in revised form 20 July 2011 Accepted 24 July 2011 Available online 6 September 2011 Keywords: Phase change materials Cold storage Active food packaging Paperboard abstract Warm temperature spikes represent one of the main spoilage causes of perishable good-stuffs. The devel- opment of packaging materials with thermal buffering properties represents a powerful solution to address the problems arising from an uncontrollable interruption during cold-chain logistic. Here, we propose the use of phase change material (PCM) composites for the design of cold storage packaging. Two different concentrations (25 and 50% w/w) of commercially available micro-encapsulated PCM were homogeneously dispersed in paper matrix via conventional negative filtration techniques. The possibility of obtaining composites with different latent heats in the 4–10 °C range has been demon- strated via differential scanning calorimetry measurements. Heat transmission tests, simulating the heat- ing processes typical of the removal from a cold room, were performed on a suitable multilayer configuration. The obtained materials show the ability to maintain the inner temperature for a duration up to 10-fold longer in time, when compared to a similar cellulose material with a thickness of 2 cm. Experimental results have been numerically assessed by considering the material thermal parameters as homogeneous. Both experimental and computational approaches here discussed offer an easy way for the design of micro-encapsulated PCM–cellulose composite as building blocks in cold storage packaging design. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Perishable good-stuffs are a large class of products, ranging from fresh foods (sometimes of high values, such as live seafood) to vaccines and blood [1], whose quality preservation over time has a huge economic and social impact. The shelf-life of these products results from a complex combination of both their physi- cal and chemical characteristics (intrinsic factors) and the external environment (extrinsic factors) [2]. One of the main extrinsic factors affecting the quality of perish- able products is represented by temperature variations during storage and distribution stages. Despite the efforts of product man- ufacturers and logistic providers, unwanted warming over accept- able product temperatures still remains a significant cause of product failure in temperature-sensitive products [1]. These warm temperature spikes have often duration up to several hours, suffi- cient to cause product spoilage [3], and are generally correlated to a temporary uncontrolled exposition to incompatible temperatures or passages in unrefrigerated areas [4]. Packaging materials play a significant role in controlling the temperature of carried goods. Usually, the limited thermal insula- tion and poor thermal buffering capacity of the standard containers do not provide any protection to unwanted warming. One possible approach to control thermal insulation and maintain a desired temperature, for a limited period of time, is represented by thermal energy storage approach [4]. Along this direction, large quantity of thermal storage/recovery can be achieved in the form of melting/ freezing latent heat by using phase change material (PCM) [5,6]. PCMs are materials that undergo a phase change, e.g. from solid to liquid state, at a specific temperature (or in a narrow range of temperatures) near envisaged application. In such systems, energy is stored during melting and recovered during freezing [7]. The la- tent heat is the thermal energy that needs to be absorbed or re- leased when PCMs change phase and are hence capable to store or release large amounts of energy [8]. Because of their great capacity to absorb and slowly release the latent heat, if a PCM is added to the interior of packaging, it increases the thermal energy storage capacity of the container [4], representing the most ideal solution for off peak storage [9]. The use of PCM allows to obtain little or no change in temperature during transition processes [5,10]: heat storage and delivery, in facts, occur over a fairly 0306-2619/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2011.07.039 ⇑ Corresponding author at: Dipartimento di Chimica, Materiali e Ingegneria Chimica ‘‘Giulio Natta’’, Politecnico di Milano, Via Mancinelli 7, 20131 Milano, Italy. Tel.: +39 02 2399 3161; fax: +39 02 2399 3180. E-mail addresses: lucio.melone@polimi.it (L. Melone), lina.altomare@polimi.it (L. Altomare), alberto.cigada@polimi.it (A. Cigada), luigi.denardo@polimi.it (L. De Nardo). Applied Energy 89 (2012) 339–346 Contents lists available at SciVerse ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy