Pengaruh Filling Ratio dan Fluida Kerja Terhadap Kinerja Closed Loop Pulsating Heat Pipe dengan Fluida Kerja Air-Etanol dalam Menurunkan Temperatur Loteng Gedung = Effect of Filling Ratio and Working Fluid on the Performance of Closed Loop Pulsating Heat Pipe with Water-Ethanol Working Fluid in Reducing Building Attic Temperature