Wastewater heat pump system

Abstract

Provided herein are water distribution systems and methods of operating water distribution systems that include a heat pump transferring heat between a first water stream dispensed into a space and a second water stream collected after use of the first water stream in the space. The heat pump can efficiently and effectively raise the temperature of the first water stream to a comfortable level for a user. In some embodiments, the first water stream may be further conditioned and/or processed downstream from the heat pump prior to being dispensed, e.g., using a mixing valve, a water storage tank, and/or a thermal storage device. In some embodiments, one or more operating parameters of the heat pump may be controlled according to a desired temperature of the first water stream being dispensed into the space.

What is claimed is: 
     
         1 . A water distribution system comprising:
 an outlet dispensing a first water stream into a space, wherein use of the first water stream in the space produces a second water stream;   a receptacle collecting the second water stream; and   a heat pump circulating a working fluid for transferring heat between the first water stream and the second water stream, wherein the first water stream flows through the heat pump toward the outlet and heat is transferred between the working fluid and the first water stream, and wherein the second water stream flows from the receptacle through the heat pump and heat is transferred between the working fluid and the second water stream.   
     
     
         2 . The water distribution system of  claim 1 , wherein the heat pump absorbs heat from the second water stream into the working fluid and the heat pump rejects heat from the working fluid into the first water stream to raise a temperature of the first water stream. 
     
     
         3 . The water distribution system of  claim 1 , further comprising a mixing valve receiving the first water stream and a third water stream, wherein the mixing valve combines the first and third water streams upstream from the outlet. 
     
     
         4 . The water distribution system of  claim 3 , wherein the mixing valve is positioned between the heat pump and the outlet. 
     
     
         5 . The water distribution system of  claim 4 , wherein a temperature of the third water stream entering the mixing valve is lower than a temperature of the first water stream entering the mixing valve. 
     
     
         6 . The water distribution system of  claim 1 , further comprising a storage tank positioned between the heat pump and the outlet, the storage tank receiving the first water stream and storing a volume of the first water stream upstream from the outlet. 
     
     
         7 . The water distribution system of  claim 6 , wherein the storage tank receives a third water stream and stores a volume of the first and third water streams upstream from the outlet. 
     
     
         8 . The water distribution system of  claim 1 , further comprising a thermal storage device positioned between the heat pump and the outlet, the thermal storage device absorbing heat from the first water stream and/or the heat pump. 
     
     
         9 . The water distribution system of  claim 8 , wherein the thermal storage device contains a heat storage material absorbing the heat from the first water stream and/or the heat pump. 
     
     
         10 . The water distribution system of  claim 9 , wherein the heat storage material comprises a phase change material. 
     
     
         11 . The water distribution system of  claim 8 , wherein the thermal storage device receives a third water stream and rejects heat into the third water stream. 
     
     
         12 . The water distribution system of  claim 11 , wherein a temperature of the third water stream entering the thermal storage device is lower than a temperature of the first water stream exiting the heat pump. 
     
     
         13 . The water distribution system of  claim 1 , wherein the heat pump comprises a first heat exchanger and a second heat exchanger, the working fluid circulating between the first heat exchanger and the second heat exchanger, wherein the first heat exchanger transfers heat between the working fluid and the first water stream, and wherein the second heat exchanger transfers heat between the working fluid and the second water stream. 
     
     
         14 . The water distribution system of  claim 13 , wherein the heat pump comprises a compressor coupled between the first and second heat exchangers and pressurizing the working fluid. 
     
     
         15 . The water distribution system of  claim 1 , further comprising a controller controlling at least one operating parameter of the heat pump according to a desired temperature of the first water stream being dispensed into the space. 
     
     
         16 . A method of operating a water distribution system, the method comprising:
 dispensing a first water stream into a space via an outlet, wherein use of the first water stream in the space produces a second water stream;   collecting the second water stream; and   transferring heat between the second water stream and the first water stream via a heat pump located upstream from the outlet to control a temperature of the first water stream being dispensed into the space.   
     
     
         17 . The method of  claim 16 , further comprising combining the first water stream with a third water stream via a mixing valve positioned between the heat pump and the outlet, wherein a temperature of the third water stream entering the mixing valve is lower than a temperature of the first water stream entering the mixing valve. 
     
     
         18 . The method of  claim 16 , further comprising storing a volume of the first water stream in a storage tank positioned between the heat pump and the outlet. 
     
     
         19 . The method of  claim 16 , further comprising:
 absorbing heat from the first water stream and/or the heat pump via a thermal storage device positioned between the heat pump and the outlet; and   rejecting heat into a third water stream using the thermal storage device.   
     
     
         20 . The method of  claim 16 , further comprising controlling at least one operating parameter of the heat pump according to a desired temperature of the first water stream being dispensed into the space.