12 Volt Thermoelectric Water Chiller - A Comprehensive Review

This is a 180 watt thermoelectric water chiller which utilizes a solid-state peltier element as the active heat pump. Since it was purchased a while back from an online retailer, it is a prepackaged unit complete with a chiller block through which water circulates through to release its heat into the peltier element, and a heatsink/fan combination to dissipate the total heat which consists of heat collected by the chilled water and Joule heating within the peltier.

The unit is powered by a micro-ATX computer power supply which was salvaged from an old computer. Since the power supply is rated to supply 15 amperes at 12 volts, its power output is just sufficient to satisfy the input power of the peltier element.

To fully utilize the cooling potential of the unit, I am using a setup which circulates chilled water through a single 120mm air-liquid heat exchanger. A DC brushless fan is used for forced convection across the chilled water radiator to aid heat transfer from the ambient to the circulating liquid. A single DC pump operating off 5 volts is sufficient to overcome pressure drop through the chiller, and radiator.

Three temperature measurements of the chilled water exiting the chiller block clamped on top of the peltier's cold side were taken.
The first temperature measurement with the radiator fan switched off yielded a chilled water supply (CHWS) temperature of an impressive 3 degrees Celsius.
The second CHWS measurement yielded approximately 13.5 degrees Celsius after the radiator fan was operating at 5 volts for up to five minutes.
The third and final temperature measurement was taken after the unit was allowed to achieve steady-state steady-flow condition, and the CHWS temperature was measured to be between 16 to 17 degrees Celsius.

The raw performance benchmarks of this unit should not come off as a surprise to anyone since there are several reasons which result in a reduced coefficient of performance for a peltier element including: inadequate heat dissipation from the heat pump's heatsink, unintentional heat transfer into the closed loop system through convection and radiation into the matte blue chilled water block, and operating the module close to its maximum current (I_max) which leads to increased Joule heating.

The issue related to inadequate heat dissipation from the peltier's hot side can be solved by replacing the air cooled heat-pipe based heatsink with a solution that exploits water's high latent heat. This can be achieved by routing the coolant through a scaled down evaporative cooling tower similar to the ones which cool the condensers of industrial chillers found in process, and large scale HVAC applications for commercial buildings.

To learn more about thermoelectric heat pumps, you are encouraged to read Wikipedia's own article on Thermoelectric Cooling:
https://en.wikipedia.org/wiki/Thermoelectric_cooling

How commercial buildings are cooled with refrigerant based mechanical chillers:
https://www.youtube.com/watch?v=gYcNDT1d30k