Applied Energy 113 (2014) 1525–1561 Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy Review A review of phase change materials for vehicle component thermal buffering ⇑ Nicholas R. Jankowski a,b, , F. Patrick McCluskey b a Sensors and Electron Devices Directorate, U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783, USA b Department of Mechanical Engineering, University of Maryland, 3135 Glenn L. Martin Hall, College Park, MD 20742, USA highlights A review of latent heat thermal energy storage for vehicle thermal load leveling. Examined vehicle applications with transient thermal profiles from 0 to 800 °C. >700 materials from over a dozen material classes examined for the applications. Recommendations made for future application of high power density materials. article info abstract Article history: The use of latent heat thermal energy storage for thermally buffering vehicle systems is reviewed. Vehicle Received 2 August 2012 systems with transient thermal profiles are classified according to operating temperatures in the range of Received in revised form 24 July 2013 0–800 °C. Thermal conditions of those applications are examined relative to their impact on thermal buf- Accepted 9 August 2013 fer requirements, and prior phase change thermal enhancement studies for these applications are dis- Available online 4 October 2013 cussed. In addition a comprehensive overview of phase change materials covering the relevant operating range is given, including selection criteria and a detailed list of over 700 candidate materials Keywords: from a number of material classes. Promising material candidates are identified for each vehicle system Review based on system temperature, specific and volumetric latent heat, and thermal conductivity. Based on the Phase change material Thermal management results of previous thermal load leveling efforts, there is the potential for making significant improve- Vehicle systems ments in both emissions reduction and overall energy efficiency by further exploration of PCM thermal Thermal buffering buffering on vehicles. Recommendations are made for further material characterization, with focus on Energy efficiency the need for improved data for metallic and solid-state phase change materials for high energy density applications. Published by Elsevier Ltd. Contents 1. Introduction . ..................................................................................................... 1526 2. Vehicle thermal buffer applications . .................................................................................. 1527 2.1. Low temperature vehicle applications, T < 100 °C..................................................................... 1528 2.1.1. Energy storage for cold start improvement . .......................................................... 1528 2.1.2. Cabin climate system thermal buffering . .......................................................... 1528 2.1.3. Absorption air conditioning loop thermal buffering. .......................................................... 1529 2.1.4. Cabin payload systems, electronics thermal protection . ....................................... 1529 2.1.5. Vehicle battery thermal buffering . .......................................................... 1530 2.2. Medium temperature vehicle applications, 100 °C<T < 200 °C.......................................................... 1531 2.2.1. Engine coolant loop thermal buffering . .......................................................... 1531 2.2.2. Vehicle power electronics thermal buffering . .......................................................... 1531 2.3. High temperature vehicle applications, T > 200 °C .................................................................... 1532 ⇑ Corresponding author. Address: U.S. Army Research Laboratory, ATTN: RDRL- SED-E, 2800 Powder Mill Road, Adelphi, MD 20783-1197, USA. Tel.: +1 301 394 2337; fax: +1 301 394 1801. E-mail address: [email protected] (N.R. Jankowski). 0306-2619/$ - see front matter Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.apenergy.2013.08.026 1526 N.R. Jankowski, F.P. McCluskey / Applied Energy 113 (2014) 1525–1561 Nomenclature TEG thermoelectric generator Acronyms/abbreviations U.S. United States USABC U.S. Advanced Battery Consortium AC air conditioning CAS Chemical Abstracts Service Symbols C2 command and control c specific heat at constant pressure (kJ/kg K) CO carbon monoxide p k thermal conductivity (W/mK) DOD U.S. Department of Defense th H latent heat (kJ/kg) DOE U.S. Department of Energy n formula number ECU engine control unit T temperature (°C) EHR exhaust heat recovery wt% weight percentage EV electric vehicle HC hydrocarbon Greek symbols HEV hybrid electric vehicle 3 HTF heat transfer fluid q density (kg/m ) kph kilometers per hour (km/h) LPG liquefied petroleum gas Subscripts PCM phase change material M melting PHEV plug-in hybrid electric vehicle f fusion RoHS Restriction of Hazardous Substances l liquid SWaP size, weight and power s solid TES thermal energy storage t transition TCU temperature control unit v volumetric TE thermoelectric 2.3.1. High temperature exhaust energy storage for cold start improvement . .......................... 1532 2.3.2. Exhaust energy buffering for waste energy electrical conversion . ............................................. 1532 2.4. Summary of vehicle appropriate thermal buffer applications ........................................................... 1533 3. Phase change material overview ........................................................................................ 1534 3.1. PCM reviews and material coverage . ........................................................................... 1534 3.1.1. Earlier studies and PCM selection criteria. ................................................................ 1534 3.1.2. Recent PCM coverage and temperature range expansion . ............................................. 1535 3.1.3. Comments on reported commercial phase change materials . ............................................. 1536 3.2. Phase change materials by category . ........................................................................... 1537 3.2.1. Organic materials . ................................................................................ 1537 3.2.2. Inorganic materials. ................................................................................ 1538 3.2.3. Solid–solid phase transition materials . ................................................................ 1540 3.3. Summary of available PCMs . ........................................................................... 1541 4. PCM comparison for vehicle applications . ..................................................................... 1541 4.1. Low temperature materials, T < 100 °C ............................................................................. 1542 4.2. Medium temperature materials, 100 °C<T < 200 °C................................................................... 1543 4.3. High temperature materials, T > 200 °C............................................................................. 1544 4.4. Comments on PCM thermal buffer cost implications . ........................................................... 1545 5. Recommendations and conclusions . ..................................................................... 1546 Disclaimer . ............................................................................................ 1557 Appendix A. Full material tables ..................................................................................... 1557 References . ........................................................................................................ 1557 1. Introduction improving the management of vehicle heat is critical to achieving higher platform efficiency [2,3]. Depending on operating condi- Fuel economy has long been a dominant design goal for com- tions, typical vehicles reject approximately 65–75% of the fuel’s en- mercial vehicles, but recently issued U.S. Department of Defense ergy as waste heat through the exhaust or radiator, and in current (DOD) policy has set increased energy efficiency and fuel economy combat vehicles about 10–15% of the useful energy is devoted to as immediate priorities for military vehicles as well, putting running the cooling system [4,5]. emphasis on the strategic and operational impact of the military’s A number of investigations have been directed at improving overall energy usage [1]. System level analyses by both the DOD overall vehicle thermal efficiency, but these efforts are complicated and the U.S. Department of Energy (DOE) have recognized that by the transient nature of the vehicle’s thermal load. As shown in N.R. Jankowski, F.P. McCluskey / Applied Energy 113 (2014) 1525–1561 1527 Fig. 1, over any given drive cycle a vehicle can have peak velocity Past studies have attempted to cover PCMs and their use in the and power demands much higher than the average values, with aforementioned applications, but the overall vehicle system has sudden load changes occurring multiple times over the cycle been only tangentially addressed, prompting this report which at- [6,7]. Most vehicle thermal management systems are designed to tempts to provide a consolidated review of vehicle component handle expected worst case conditions as steady-state require- thermal buffering. Section 2 of this paper classifies vehicle systems ments. However, using the drive