An　experimental　system　of　parabolic　trough　solar　collector　and　heat　transfer　was　set　up　with　a　new　molten　salt　employed　as　the　heat　transfer　medium　(with　a　melting　point　of　86　degrees　C　and　a　working　temperature　upper　limit　of　550　degrees　C).　The　circulation　of　molten　salts　in　the　system　took　place　over　1000　h.　Experiments　were　conducted　to　obtain　the　heat　loss　of　the　Heat　Collector　Element　(HCE),　the　total　heat　transfer　coefficient　of　the　water-to-salt　heat　exchanger,　and　the　convective　heat　transfer　coefficients　for　the　low　melting　point　molten　salt　in　a　circular　tube.　The　results　show　that　the　thermal　loss　of　the　tested　HCE　is　higher　than　that　of　the　PTR70,　and　the　thermal　loss　at　the　joints　of　the　collector　tube　represents　about　5%　of　the　total　loss　in　the　entire　tube.　The　total　heat　transfer　coefficient　of　the　water-to-salt　heat　exchanger　was　between　600　and　1200　W/(m(2).k)　in　the　ranges　of　10,000　＜　Re　＜　21,000　and　9.5　＜　Pr　＜　12.2.　The　experimental　data　show　good　agreement　with　existing　well-known　correlations　presented　by　the　Sieder-Tate　equation　and　the　Gnielinski　equation.　This　experimental　study　on　heat　loss　from　molten　salt　flow　in　a　receiver　tube　will　hopefully　serve　as　a　helpful　reference　for　applications　in　parabolic　trough　systems.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.