Da Vinci Co., Ltd

Rotary Heat Engine (RHE)

Rotary Heat Engine System

Openable documents about RHE are provided in this page.
For more detailed information, we will offer you as much as necessary
after signing a confidential agreement.
If you need an estimated performance which are not rated in this page,
please contact us from here.


Introduction of Rotary Heat Engine

Rotary Heat Engine (RHE) is Wankel-based Rotary Engine with designated external combustion driven by Rankine cycle. Rankine cycle works at the temperature around the boiling point of working fluid. Thus, by using the working fluid of low boiling point, we can generate electricity from low temperature heat source. When using HFC245fa as working fluid in Da Vinci's RHE, we can generate electricity from 40℃ of waste heat (liquid) and 25℃ of cooling water.

For instance, in case of storing and circulating 85℃ of waste heat in the heat storage tank, we can generate electricity until the hot water becomes 50℃. As a result, the total electric generation amount would be larger than other companies' technology.

On the other hand, we cannot abandon high temperature industrial waste water. So, we often need to pour a large amount of industrial water to cool down the waste water to 50℃. In this case, by installing Da Vinci's RHE, you will be able to obtain electricity in the process of cooling down the waste water. As a result, the system will be improved in economy.

In this page, we will explain the details of RHE.
For more detailed information, please refer to our RHE technical document or visit the Members Site.



Impulsive type engine, such as turbine, generally uses dynamic pressure and converts to rotational energy, so it needs high temperature heat sources. On the other hand, displacement type engine, such as Da Vinci's RHE, uses static pressure and converts to rotational energy. Therefore, it works even in low pressure.

Our RHE can work with 40℃ heat source if the temperature of cooling water is 20℃. However, in other expander such as turbin, the working fluid would be condensed and become liquid in low temperature, and this may lead to the breakdown of the system. Our RHE system has the best heat work efficiency which can generate from low temperature (70-100℃) heat source. In the future, more and more demands for reusing low temperature waste heat. Da Vinci's system can supply that demand!


Application of RHE System

Currently, our company is selling 10kW RHE system. In the future, we are planning to sell 18kW RHE system (Twin Engine Unit) which consists of two 10kW RHE systems. Twin engine unit can generate 18kW of electricity. The one RE expander works as an expander, and the other one works as a compressor. This system exchanges waste heat for cold heat.

By combining several twin engine units, it will be possible to construct 200kW generation system (see the figure below).

Latent Heat Regeneration Cycle

This cycle represents recuperator. It collects heat which wasn’t used in RHE expander, and reuse that heat in the cycle. The data in the figure is the measured value at RIKEN.
As we reuse 50% of circulated heat amount in the cycle, input heat amount will be reduced and the heat work efficiency will be double.

RHE Heat Pump

The figure shows the simulation of RHE heat pump which uses both condenser of heat pump and RHE evaporator. The power consumption of compressor is reduced by RHE’s generated electric power.

Application for Radiant Energy and Electricity Generation

Da Vinci is developing a system of collecting radiant energy for electricity generation with Radiant Energy and Electricity Generation Research Team (REEG) at RIKEN. Radiant energy is thermal (or heat) energy originated from any light, such as sunlight. The advantage of converting light energy to thermal energy is that storing heat is much easier than storing electricity. By storing heat collected from sunlight, we can generate electricity the amount of stored heat whenever necessary. Radiant energy and electricity generation have the possibility of being Da Vinci's business core technique in the future.

For more detailed information, please refer to our technical document.