HomeNature’s Refrigerator: The Mechanics of Lake Source Cooling
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Nature’s Refrigerator: The Mechanics of Lake Source Cooling

As its name implies it Lake Source Cooling relies on, well, a lake–Cayuga Lake, specifically.

The specific heat of water is behind how LSC works.  Compared to other materials, water has a very high specific heat, meaning it has a lot of capacity to absorb heat from its surroundings before its temperature changes.  Formally, specific heat is widely known as the amount of heat that you need to raise the temperature of 1 gram of a substance by 1 degree Celsius. Water’s characteristically high specific heat makes it ideal for cooling purposes.

Gravity-feed System and Pumps 

Gravity-feed system
 Cold water is transferred from the bottom of Cayuga lake to the LSC plant without the use of a pump. Since the intake pipe is located so far below the surface level of the lake, the cold water actually flows upwards based on the laws of fluid dynamics. In order to get the chilled water from the plant up to campus, pumps operate. The speed of these pumps is controlled through breakers which allows for pump energy only to be used when necessary.

 

So just how does this come into play in LSC?  Well, the way LSC is designed is that it uses a series of two main loops of pipe (pictured above).  One of these loops carries cool water from the depths of Cayuga Lake while the other carries water from Ithaca High School and Cornell University’s campuses.  The pipes meet at a series of metal plates called heat exchangers.

 

The Heat Exchangers

The Heat Exchangers
The LSC has 7 plate and frame heat exchangers capitalize on counter-current flows of water to maximize efficiency. Water from the lake flows on one side of the plates, while water from campus flows on the other, with only heat exchanged.

 

This is where it takes advantage of the specific heat of water and the fact that heat flows from hotter to colder objects.  At the interface between the two pipes, the heat exchangers facilitate the exchange of heat from the warmer campus pipes to the cooler lake pipes.  The cool water coming into campus buildings can then absorb heat from these buildings and cycle through again to be cooled (2).

 

ROVS and Cleaning

ROV's and Cleaning
Underwater robots are used to perform inspections of the pipes and intake screen. https://www.gdiving.com/project/cornell-lake-source-cooling-cleaning/

 

The beauty of this system is that it is almost entirely renewable.  The only energy required is to overcome the friction in the looped pipes, resulting in a system that is 85% more efficient than the traditional cooling systems and does not use any chemicals (1).  The plant is also 100% remote operated and maintained though control boards operated from Cornell’s heating plant. LSC is incredibly simple yet brings amazing benefits in terms of energy savings and sustainability.