China News Service, Jinan, September 17 (Zhou Yiwei, Yu Qing) "The thermal physical properties of geotechnical parameters are an important basic reference for the development and utilization of shallow geothermal energy. The performance of the testing equipment directly determines the scientific nature of the development plan, the stability of the project operation and the effectiveness of energy saving." In the Fourth Exploration Team of the Shandong Provincial Coalfield Geology Bureau (hereinafter referred to as the "Fourth Exploration Team"), Yang Chuanshi, head of the Low Carbon Energy Technology Development Department, introduced the constant power geothermal physical property tester independently developed by the team.
The picture shows a constant-power geothermal physical property tester carrying out testing operations in the field. Photo by Gao Peng
For a long time, there have been interfering factors such as voltage fluctuations, complex stratigraphic conditions, and insufficient test accuracy at shallow geothermal field testing sites. Traditional testing equipment is prone to problems such as unstable heating power and large temperature measurement errors, causing distortion of key parameters such as geotechnical thermal conductivity. This causes the design of underground pipes to deviate from reality, posing hidden dangers to subsequent ground source heat pump system designs. Yang Chuanshi said that after the completion of some projects, the heat exchange efficiency did not meet the standards, and phenomena such as high energy consumption and accumulation of cold and heat occurred, which affected the long-term operation results of the projects.
"We found in some on-site measurements that the actual power of the heating equipment with a rated power of 3kW was only 1.8kW during the peak period of electricity consumption. The voltage fluctuated greatly and the heating power was unstable, which ultimately led to deviations in the calculation of geothermal conductivity." Yang Chuanshi said that at present, most of the test equipment focuses on laboratory scenarios, lacks portability, and the software and hardware are separated. Data analysis relies on manual processing, and the work efficiency is low. Complex stratum test errors are difficult to control, and are not suitable for complex field engineering sites.
Yang Chuanshi admitted that traditional test data only serves one engineering project and lacks a unified collection method. A large number of precious measured geothermal and physical property data under different geological conditions cannot be summarized and formed into a database. The value of data reuse is difficult to realize. It cannot provide accurate and systematic data support for the evaluation of shallow geothermal resources in the entire region and the feasibility prediction of the project.
The picture shows technicians debugging the constant power geothermal physical property tester before starting the test work. Photo by Yang Bin
In response to the above-mentioned industry pain points, the Fourth Exploration Team organized professional and technical forces to carry out concentrated research. In terms of hardware technology innovation, the team pioneered constant power heating technology, which achieves stepless power adjustment from 2.5kW to 4kW and supports constant power heating with a wide voltage of 180V to 250V. It effectively resolves test interference caused by power supply voltage fluctuations at field construction sites and ensures the continued stability of heating conditions from the source. The temperature measurement resolution of the equipment has also been increased from 0.1℃ in the past to 0.01℃, and the temperature measurement accuracy has achieved an order of magnitude jump.
At the same time, the equipment is equipped with dual-parameter intelligent analysis software independently developed by the team, which can automatically generate rock layer histograms, build geotechnical databases, and create an integrated process of "on-site hardware acquisition + software automatic analysis", which greatly reduces test errors under complex stratigraphic conditions and fully meets the requirements of national standard constant power testing.
"The equipment is only the size of a suitcase and can be taken anywhere, which is very convenient." Yang Chuanshi told reporters that after multiple rounds of iterative optimization, at present, the overall technology of the fifth-generation constant power high-precision intelligent thermal physical property testing technology equipment has reached the domestic leading level, filling the gap in the domestic field of high-precision rock and soil thermal physical property testing equipment. This equipment has obtained invention patents, computer software copyrights, and has complete independent intellectual property rights.
At the same time, in the process of overcoming technical bottlenecks, the project team actively explored working paths for adapting laboratory technical results to field engineering scenarios, and established a closed-loop industry-university-research transformation method of "scientific research - test instrument iteration - field application". The team uses a real ground source heat pump project as a test carrier, relies on the first set of policies to promote continuous iterative upgrades of equipment, innovatively implements an integrated industrial model of "accurate testing-meticulous design-standardized construction", and transforms intellectual property achievements such as patents and software copyrights into mass-produced commercial equipment, forming a replicable and promoteable shallow geothermal energy industry-university-research transformation paradigm.
At present, the above-mentioned technological achievements have been widely promoted in more than 10 provinces and cities, including Beijing, Shandong, Henan, and Hebei, serving more than 50 domestic geological survey and new energy engineering units, and applied in more than 70 ground-source heat pump survey and geothermal physical property experimental test projects. At the same time, the equipment is also exported overseas. The cumulative contract value for equipment sales and technical services has reached nearly 10 million yuan (RMB, the same below), driving the shallow geothermal energy-related industries to achieve economic benefits of hundreds of millions of yuan, and annual carbon emission reductions of 100,000 tons, achieving a win-win situation for both economic and ecological benefits.
"Equipment accuracy, stability, and field adaptability determine the accuracy of geothermal resource evaluation and the quality of subsequent engineering design and construction, and are directly related to whether the project's energy saving and carbon reduction goals can be truly realized." Li Haibo, secretary of the party committee and captain of the Fourth Exploration Team, said that the team will continue to deepen the iterative upgrade of core technologies, improve the technical service system, expand technology application scenarios, and empower the high-quality development of shallow geothermal energy with innovation in geological science and technology equipment.
