Solar Thermal Waste Heat Engine works at low temperature, low pressure
By Paul Evans
February 12, 2009
February 13, 2009 Technology capable of generating electricity by extracting energy from heat that is otherwise just wasted is a fairly new branch of renewable technology. A typical co-generation plant uses waste heat from a gas or steam turbine for hot water or space heating. This Waste Heat Engine (WHE) developed by Cyclone Power Technologies operates at temperatures as low as 225F (107 C). The engine can generate up to 10kw from heat sources such as industrial ovens or furnaces, concentrating solar thermal collectors, engine exhaust and biomass combustion.
The compact, lightweight 18 lb (8 kg) Waste Heat Engine is a six-cylinder radial steam engine capable of running on waste heat as low as 225 °F (107 °C) and pressure as low as 25 psi (172 kPa). The engine achieves maximum efficiencies at 600 °F (316 °C) and steam pressure of 200 psi (1.4 MPa), at which point one Waste Heat Engine can generate 16 hp (12 kW), 30 lb-ft (41 Nm) of torque, and a little over 10 kW of electrical output. The only drawback is the typically low 12% energy efficiency common with most reciprocating steam engines. On the plus side the piston-based steam engine operates at a maximum of 3000 rpm which means it is well suited to drive any standard generator.
Due to its patent-pending valve mechanism and radial spider bearings, which allow for efficient piston movement, the WHE will self-start immediately upon the introduction of steam to the cylinders. This makes the engine well suited for passive or secondary energy production like co-generation or small scale solar thermal applications.
Over the following months, the company's new WHE/Generation division will launch a consumer-oriented web site, and contract with manufacturers and installers to handle forecasted sales of these systems.
The first WHE system will be installed at Bent Glass Design in Hatboro, PA. This system will harness waste heat from the customer’s glass manufacturing furnaces, and is expected to produce enough electricity to light their 65,000 ft2 facility while providing a quick payback possibly within two or three years.