Introduction to Thermoacoustics
Thermoacoustic Effect allows conversions between mechanical energy and thermal energy by using sound waves (aka “pressure waves”) as medium. The process starts with the gas being heated in the “hot region”, a treatment that inflates gas volume. The inflation then results in the gas being pushed into the region of lower temperature, the “cool region”, and this relocation shrinks gas volume as previously acquired heat is losing. Simultaneously, inflated gas creates sound waves that spread outwards at the speed of sound, causing wave reflections in certain mechanic structures such as tubes and chambers. Consequently, gas that was losing heat during the preceding mechanism returns to the hot region, where the gas is re-inflated. This process of gas inflation and re-inflation altogether forms a cyclical heat-sound self-excitation, thus the name of “thermo (heat) acoustics (sound)”.
Thermoacoustic applications can be done both in forward (“positive”) processes or backward (“negative”) processes. During forward processes, thermal mechanisms lead to the creations of sound waves, which could be transformed into mechanical energy. Thermoacoustic engine, a new form of heat engine, works based on such forward processes. The backward processes work in exactly the opposite way. In certain mechanic structures, sound waves produced by other equipment lead to the “pump-heating” phenomena. The pump-heating effect allows manipulation of temperature by acoustic impacts on gas volume. Through fine acoustic designs, backward Thermoacoustic processes can be used to produce cryocoolers and heat pumps.
Lihan's Story: A Decade of Innovation
2007: A Humble Start
Dr. Luo Ercang, our chief scientist who is also affiliating with the Chinese Academy of Science, was awarded the Hu Gangfu Prize, the highest honor in Physics in China, for making theoretical breakthrough in the field of thermoacoustics.
Our company, Lihan, was born in July of the same year, with the mission to translate Dr. Luo’s theoretical contributions into high qualitied industrial products.
2008-2013: Years of Research and Recognition
We devoted ourselves to research in the first few years of our company. Major efforts include thermoacoustic solar generator and thermoacoustic cryocooler, etc. We received multiple recognitions for our efforts, notably Municipal High-tech Company of Shenzhen (2008), winner of the China Innovation Entrepreneurship Competition (2009), and grand prize for Industrial Design in China Electrical Equipment Competition (2013).
2014: The Birth of Lihan Cryogenics Co. Ltd
As our technology in cryogenics matured, we decided to establish a subsidiary concentrating solely on thermoacoustic cryogenics. The result was the birth of Lihan Cryogenics Co. Ltd. The new company features a group of energetic, talented researchers and engineers, as well as a new facility which consistently manufacturing high quality cryocoolers.
2015: Commercial Breakthroughs and Continuing Research
In 2015, we formally establish long-term partnership with a global leading firm in nuclear industry.
We are also continuously devoting our most of our resources into R&D, ranging from power generation to heat pumping.
Applictions of Thermoacoustics
Application 1: Thermoacoustic Cryocooler
Our cryocooler use independently developed air-floatation linear oscillation engines which, by opposed positioning, reduce vibration to nearly undetectable level. This feature makes our cryocoolers especially suitable for vibration-level demanding environments.
We also successfully get rid of moving parts in cold-finger: this not only reduces vibration, but also improves the cold-finger’s impact resistance by avoiding internal dysfunction caused by lateral acceleration.
Furthermore, we developed dedicated SPWM controllers for each model of our cryocoolers. They allow users to control refrigeration accurately even in extremely demanding applications. All these features-low vibration, cold-finger impact resistance, great life performance and accurate controlling-make our cryocoolers ideal solutions in cryogenic platforms.
Application 2: Thermoacoustic Engine
Our thermoacoustic engines convert thermal energy into mechanical energy through the “forward (positive)” of thermoacoustic effect. Thermoacoustic engine is a platform technology that can be used in a wide range of applications involving thermal-mechanical engine conversion. Thermoacoustic engine, as an external combustion engine, is more environmental friendly than traditional internal combustion engine by consuming solar energy, biomass and industrial residual heat instead of polluting fossil energy sources.
Our thermoacoustic engine achieves thermal cycling primarily through gas rather than mechanical processes. As a result, its internal structure, similar to that of our cryocoolers, is largely free of moving parts, making it more reliable and cost-efficient than traditional engines.
Application 3: Thermoacoustic Heat Pump
Our thermoacoustic heat pump works through the “backward (negative) process” of thermoacoustic effect. Using linear oscillation engine, our heat pump first converts electric energy into pressure wave (acoustic energy), and then creates difference-in-temperature on Thermoacoustic units (i.e. regions where thermoacoustic effect takes place). Heat pump is achieved through simultaneous processes at both the cold-end and the hot-end of a thermoacoustic unit: at the cold-end, heat exchange is carried out by interacting with ambient temperature by a cooling radiator; at the hot-end, where heat pump effect occurs, temperature increases under acoustic influences.
Thermoacoustic Heat Pump is more efficient than traditional electric heating. In terms of civil and industrial high-temperature acquiring, our thermoacoustic Heat Pump is expected to be 2~3 times as efficient as mainstream electric-heating devices.
Thermoacoustic Heat Pump is especially powerful in high difference-in-temperature environments: it outperforms similar products in applications that operate in high difference-in-temperature, e.g. water-heating and electric automobile heat-pumping.
Our strength in R&D has won us many scientific/engineering awards and prizes. Here is a short list of recognitions we received:
Awards & Prizes
Hu Gangfu Prize in Physics (Highest Honor in Physics in China)
Municipal High-Tech Firm, Shenzhen City
No.4, Star of Entrepreneurship Competition, Nanshan Dist., Shenzhen
Winner, China Innovation Entrepreneurship Competition
Merit Award, United Nations Industrial Development Organization
Award in Innovation, China International Industry Expo
Merit Award, Shenzhen Green Innovation Development Organization
Provincial Yearly New Product, Guangdong Province
Grand Prize, China Digital Equipment Industrial Design Competition
National High-tech Firm
Prize in Invention, Shenzhen Science and Technology Competition
Top 100 List, 4th Shenzhen Small-Medium Sized Entrepreneurship