Source: Chinese Business View Published: 2014-8-19

Inventor Zhang Kai adjusts an evaporative cooler he and his father designed to run without electricity. Photo: CFP

According to media report recently a junior high school teacher and his son in Xi’an, Shaanxi Province invented an evaporative cooler that works without electricity thus saving on utility bills..

History teacher Zhang Zizhi teamed up with his son, Zhang Kai, a college freshman majoring in electronic and information engineering, to design a cooler that works much like conventional evaporative coolers – except without an electric water pump.

“This can be useful in a tent while camping in summer,” said the elder Zhang.

According to their tests, the device is capable of cooling an average-sized room by 2 C in 10 minutes.

Standing 1.2-meters tall, the cooler consists of a metal frame with eight pieces of wet fabric hanging closely together to act as cooling pads.

Instead of using a pump to draw water onto the pads, water flows from a plastic water tank placed above the cooler.

Water flow is regulated with a drip-valve from a standard IV bag.

As hot air passes through the wet fabric, the water slowly evaporates. Water molecules are then dispersed and absorb heat from the hotter air. The larger the cooling pads, the more water evaporates.

It takes two liters of water every three hours.

The Zhangs said the device cost 60 yuan ($9.77) to build.

The father-son team seeks to develop an automatic water feeding device and replace the metal racks with a collapsible plastic frame in order to further cut costs.