Integration of phase change materials inside evacuated tube solar collector for storage and transfer of thermal energy

Abstract

An objective of the invention is to design and develop an effective method to collect and store heat in a solar collector for delayed release. An embodiment of the invention is directed to an evacuated tube collector, where PCM is placed directly inside the void space of the collector tube, next to the heat pipe. The heat pipe is located with phase change material (PCM) in such a way that its thermal connection with the heat pipe can be switched “ON” to start heat transfer from PCM or “OFF” to keep latent heat stored in PCM for delayed usage. In additional, flow of heat exchange fluid through the manifold can enable release of stored heat of PCM to storage tank. Delayed release of accumulated heat in PCM enables added functionality of on-demand operation of SWH.

What is claimed is: 
     
         1 . A solar collector comprising:
 an evacuated tube collector (ETC) or an ETC array;   a phase change material, wherein the phase change material is located within the inner space of the evacuated tube collector; and   a heat pipe, wherein the heat pipe is located within the inner space of the evacuated tube collector and wherein the heat pipe is in thermal contact with the phase change material.   
     
     
         2 . The solar collector of  claim 1 , wherein the phase change material comprises materials having high transition temperatures. 
     
     
         3 . The solar collector of  claim 1 , wherein the phase change material comprises salts. 
     
     
         4 . The solar collector of  claim 1 , wherein the phase change material is selected from the group consisting of erythritol, pentaerythritol, azelais acid, sebacic acid, dimethyl terephthalate, p-toluic acid, octadecanamide, urea, and high density polyethylene. 
     
     
         5 . The solar collector of  claim 1 , wherein the heat is stored within the phase change material. 
     
     
         6 . The solar collector of  claim 1 , wherein the thermal contact between the heat pipe and the phase change material is controlled by a switching mechanism. 
     
     
         7 . The solar collector of  claim 1 , wherein the heat pipe furthers comprise a heat transfer fluid. 
     
     
         8 . The solar collector of  claim 7 , wherein the heat transfer fluid is water. 
     
     
         9 . The solar collector of  claim 1 , wherein heat is transferred from the phase change material to the heat pipe. 
     
     
         10 . The solar collector of  claim 1 , wherein heat is transferred from the heat pipe to the heat transfer fluid. 
     
     
         11 . A solar collector of  claim 1 , wherein the heat pipe is in thermal contact with the phase change material, and heat transfer from PCM to water storage tank is controlled by water flow through a heat exchanger manifold. 
     
     
         12 . The solar collector of  claim 1 , wherein the heat transfer from PCM to the water storage tank is controlled on demand. 
     
     
         13 . The solar collector of  claim 1 , wherein carbon based materials are mixed inside the phase change material to improve heat conductivity of system. 
     
     
         14 . The solar collector of  claim 1 , wherein carbon nanotubes are added to the phase change material. 
     
     
         15 . The solar collector of  claim 1 , wherein pyrolized electrospun fibers are added to the phase change material. 
     
     
         16 . The solar collector of  claim 1 , wherein the phase change material inside the ETC tubes placed inside multiple containers. 
     
     
         17 . The solar collector of  claim 16 , wherein heat transfer oil is added inside the ETC tubes with phase change materials filled containers. 
     
     
         18 . The solar collector of  claim 1 , wherein the solar collector is used with a solar concentrating arrangement. 
     
     
         19 . The solar collector of  claim 1 , wherein the heat pipe is supported by the heat fin in the middle of the ETC. 
     
     
         20 . The solar collector of  claim 1 , wherein heat fins are placed radially.