A brief discussion on the development and applicability of water-driven fan cooling towers

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This post was last edited by WSRYLONG on 2025-7-7 at 12:07. A Brief Discussion on the Development and Applicability of Water-Motorized Fan Cooling Towers. I. A Brief Overview of the Development of Water-Motorized Fan Cooling Towers. II. A Brief Discussion on the Applicability (Limitations) of Water-Motorized Fan Cooling Towers. III. A Comparison Between Energy-Saving Technologies for Water-Motorized Fan Cooling Towers and Those for Water Pumps. A Brief Discussion on the Development and Applicability of Water-Motorized Fan Cooling Towers. I. A Brief Overview of the Development of Water-Motorized Fan Cooling Towers. In the 1970s, fiberglass cooling towers began to be used in China and gradually became more widespread; the fans used in these cooling towers were typically driven by motors. In the late 1990s, the idea of “using water turbines to replace electric motors in driving cooling tower fans” emerged in China. Active efforts were made to research, develop, and trial related products for promotion and application; as a result, this technology and its associated industries gradually developed and grew. To this day, there is no authoritative or unified name for the technology of using water turbines to drive the fans in cooling towers; various names are used for it, such as motor-free cooling towers, electricity-free cooling towers, water turbine cooling towers, energy-saving cooling towers, hydraulic fan cooling towers, hydraulic ventilation cooling towers, water kinetic energy recovery cooling towers, and so on. This article will temporarily refer to it as a “water-driven fan cooling tower,” and the turbine used in it as a “cooling tower turbine.” Looking at the development of water-driven fan cooling tower technology over the past 30 years, it is essentially a process of continuously researching and improving cooling tower water turbines to make them more applicable and efficient. In other words, the development of cooling tower water turbines reflects the development of water-driven fan cooling towers. A search of existing literature shows that the earliest documented record in China regarding the use of water turbines to replace electric motors for driving cooling tower fans can be found in Zhang Fei Kuang’s patent application disclosure dated October 29, 1998, titled “Energy-Free Cooling Tower”. Judging from its name, this patent is named with the entire cooling tower system in mind; it focuses on energy-saving cooling towers and describes mainly the system’s components, operation process, and energy-saving principles, reflecting more of an idea. Its claims include: “Claim 1 – The energy-free cooling tower is a heat and mass exchange device that combines the motor fan and water distributor of conventional cooling towers; it eliminates the need for a motor, uses hydraulic power to distribute water while simultaneously extracting air. It is characterized by being designed based on the principle of water turbines, relying on hydraulic pumps for pressure generation.” ； The liquid passes through the turbine, which converts the energy into mechanical power; this, in turn, causes the blades to rotate and generate airflow. ” Although the patent does not explicitly use terms such as “water-driven fan cooling tower,” and its specific description does not exactly match current descriptions of water-driven fan cooling towers, in essence, this patent indeed introduces for the first time in China the most novel and creative core energy-saving technology related to water-driven fan cooling towers: eliminating the fan motor and utilizing the residual energy from the cooling tower’s incoming water as a power source to drive a turbine, which in turn replaces the motor in driving the cooling tower fans. Although, objectively speaking, the core of this technology isn’t considered some advanced theory, nor is it an invention that requires extensive research and significant funding to develop, the applicant was the first to propose it and file for a patent. During the patent protection period, its claims indeed became the fundamental principle that cannot be ignored in the design of water-driven fan cooling towers going forward. In the following years, there were another twenty-odd similar patents related to energy savings in cooling towers and new types of cooling towers, but none of them broke through the core technology of using turbines instead of motors to drive the cooling tower fans; they offered no real innovations, with some merely providing revised diagrams along with descriptions of similar processes and principles. The level of novelty, inventiveness, and practicality of certain patents can be seen from this. By the way, there’s no need for everyone to be overly obsessed with so-called patented technologies. Zhang Fei Kuang was not only the first to propose the technical concept of water-driven fan cooling towers; what’s more remarkable is that he put it into practice, was brave enough to conduct experiments and develop such systems, and actively promoted their use. Regarding whether the product performance and renovation projects of Zhang Fei Kuang and his company were perfect over the following years, as well as how to judge the patent disputes, we prefer not to comment on these matters. However, in my personal opinion, Zhang Fei Kuang can be regarded as a pioneer in the technology of water-driven fan cooling towers, and this fact should be recognized and respected. Therefore, this paper provides a relatively detailed introduction to its initial development and promotion efforts. Next, based on materials collected from journals, patents, and the Internet, as well as my own practical engineering experience, I will briefly outline the development process of cooling tower turbines to share and discuss with everyone. To better introduce and facilitate understanding of the development of cooling tower turbines, we will first describe the main categories of existing cooling tower turbines: Based on their operating principles, they are primarily classified into impulse turbines, mixed-flow turbines, and shaft-extended tubular turbines (commonly referred to as duct-type turbines) ； Classified by whether a reducer is required: type with reducer, direct-drive type (without reducer). Classified by whether the turbine is installed inside or outside the wind tunnel: built-in type and external type ； Based on whether they have a single power source, they are divided into hydrodynamic turbines and hybrid turbines. The cooling tower turbines have generally gone through the following development stages: 1. Early double-action turbines (internal, directly-connected type) (1997–2005). Zhang Fei introduced that he began exploring, testing, and developing cooling tower turbines as early as the beginning of 1997, and applied for patents while developing these turbines. The article \"Design and Application of Hydraulic Air Intake for ‘Fei Kuang Cooling Towers’\" published in the internal journal \"Zhejiang Refrigeration\" on September 19, 1999, mentioned that such systems have been adopted by more than 20 companies; the water flow rate of most cooling towers is 200 m3/h or 300 m3/h, with one cooling tower each having a flow rate of 600 m3/h and 400 m3/h. In 2001, Shanghai Feikuang Cooling Equipment Co., Ltd. was registered. Operating under a commercial service model, the company mainly deals in “motorless and energy-free” cooling towers and L-series water turbines. In the article “Application of Micro-Hydraulic Turbines in Cooling Towers” published in the journal Industrial Water Treatment on March 20, 2004, it is mentioned that in the Jiangsu, Zhejiang, and Shanghai regions, “in over 100 retrofitted towers, hydraulic turbines were used to replace electric motors, and all of them have been operating normally.” ”The author of this article is Zhang Fei Kuang, manager of Shanghai Fei Kuang Cooling Equipment Co., Ltd.; the date of receipt was September 14, 2003. From June 28 to July 1, 2004, the “Conference on the Establishment of the Cooling Tower Research Society and Technical Exchange” was held in the ancient city of Yangzhou. Shanghai Fei Kuang Cooling Equipment Co., Ltd. became a member unit, and Zhang Fei Kuang’s paper titled \"Exploration on the Trend toward Zero Power Consumption in Cooling Towers\" was included in the conference proceedings. It is likely that through this conference, more people became aware of the energy-saving technology of water-driven fan cooling towers, and its impact expanded throughout the country as a result. In 2002, Zhang Feikuang summarized and made improvements regarding several issues that had arisen in previous applications. On March 27, 2002, he filed a patent titled “Cooling Tower Turbine”. This was the first patent in China to be named “Cooling Tower Turbine”; it described in detail its components and structure. It can be regarded as a phased summary of the double-acting type. When Zhang Fei was frantically developing the initial cooling tower turbines, he had no practical experience to rely on, nor an understanding of the special conditions under which they would operate; he simply used as a basis the double-action turbines used for power generation. The double-action turbines used for power generation were originally installed horizontally; in order to drive the fans in the cooling towers, the turbines used in those towers were changed to a vertical installation, which required appropriate structural modifications. Double-action turbines used for power generation are suitable for operating in conditions where there is no water pressure, whereas cooling tower turbines operate within pressurized pipelines; this undermines the basic requirements of double-action turbines. Not only is effective double action not achieved, but the flow of water also poses obstacles to the rotor, resulting in two main drawbacks: low efficiency and low output, as well as an insufficient rotation speed of the fan, which prevents effective cooling ； Secondly, it generates significant vibration and noise, which causes the main shaft seal to wear out and leak water, as well as frequent damage to the bearings; this requires the fan to be taken out for maintenance, a process that is quite troublesome. In small cooling towers with a capacity of 300 m3/h or less, the aforementioned defects are not apparent; however, various problems arise when they are used in cooling towers with a capacity of 500 m3/h or more. Overall, there was little theoretical research during this period; Zhang Fei Kuang kept exploring, experimenting, failing, researching, promoting, and applying his ideas. Driven by the demands of the market, continuous innovations and improvements took place, and it can be said that this was a stage of trial and error on Zhang Fei Kuang’s part. 2. The external axial-flow cooling tower turbine of Xihua University (2005). Before 2005, aside from Zhang Fei Kuang’s multiple articles in journals introducing cooling tower turbines, only a few related papers published by Xihua University were available; no research reports from other individuals or organizations were seen. Around 2003, in order to save energy and reduce consumption, a chemical plant in Sichuan commissioned Xihua University to research and develop a water energy recovery device for its circulating water cooling tower, which had a flow rate of 1,500 m³/h and a residual head of 15 m. Xihua University conducted research on this topic, developing axial-flow water turbines to replace motor-driven cooling tower fans in order to recover water energy; relevant papers were published in December 2004 and the first half of 2005. Furthermore, a prototype was developed in 2005 and put into actual operation at that chemical plant. Articles from 2008 reported that it was still operating normally with good performance. On November 1, 2005, Xihua University filed a patent application for the \"Water Energy Recovery Device\", which describes an external axial-flow cooling tower turbine. This project was also regarded as a key natural sciences project of the Sichuan Provincial Department of Education (2005A123) titled “Research and Development of Water Energy Recovery Technologies and New Products,” and an evaluation was conducted by the provincial department of science and technology in June 2006. This was likely the first turbine in China to reach a capacity of 1500 m3/h; it was the largest cooling tower turbine of its time, as well as the first axial-flow cooling tower turbine, unlike the double-action type which was already widely used by many users. It should have been an important aspect in the development of cooling tower turbines, but for some reason there was little promotion of them. No further research and development on such turbines were carried out, nor were any manufacturers produced or disseminated them on a wide scale; as a result, few people are aware of them, and there is little discussion about them. They failed to have a significant impact on the history of cooling tower turbine development. The author also came to know about it by chance through repeated searches. 3. The double-click improvement and standardization phase (2005–2007): Starting in 2005, some individuals with sufficient financial resources and a positive outlook on the future prospects of cooling tower turbines began to enter this industry. In 2005, a company in Nanjing purchased a patent and began investing in the development of cooling tower turbines. By August 2006, an improved double-action turbine was developed on that basis; it was used in the renovation of cooling towers, yielding good energy-saving and overall efficiency benefits. On September 28, 2006, an appraisal meeting for \"hydraulic fan cooling towers\" was held in Nanjing. According to the information provided, the company achieved sales of 15 million RMB in 2007. At the time, it was expected to generate a profit exceeding 50 million RMB in 2008. It can be said that the influx of funds and capable manufacturers has accelerated the development pace and improved the quality of cooling tower turbines, enabling them to reach a certain stage of scaled development. Zhang Puda (the daughter of Zhang Fei Kuang) filed a patent application for the \"Double-Click Frog-Sound-Type Water Turbine\" on January 22, 2007. She identified some of the problems existing in previous double-click water turbines and introduced optimizations and improvements. This marked a progression toward more rational design, greater stability in performance, and improved efficiency for the double-click water turbine series developed by Zhang Fei Kuang, as these turbines gradually became more mature and well-established. Through continuous identification and resolution of problems, as well as the learning of lessons from the period 2005–2006 and ongoing improvements, the double-click type turbine gradually reached a stable form. Its efficiency improved compared to before, and its performance became more consistent; it was the main model in use during the years up to 2007. To date, through seven or eight years of practical application and theoretical research, there is a fairly consistent understanding regarding the double-click type turbine: it has a simple structure, stable and reliable performance, and is easy to install and maintain. However, its operational efficiency is low and its output is small, making it unable to meet the requirements of cooling towers with high flow rates; it is only suitable for small towers (with a flow rate of 300 m3/h or less). 4. Development of high specific speed mixed-flow turbines (internal, with reducer) (2007–2008): Realizing that double-entry turbines were not suitable for large-flow cooling towers, this prompted efforts to research and develop new types of turbines for such cooling towers. On June 22, 2007, someone applied for a patent for the “Reaction-type turbine for cooling towers”. This is the earliest documentation regarding reaction mixed-flow turbines with reducers for use in cooling towers. According to the information on a company’s website, in 2007 they “developed a reaction-type mixed-flow turbine equipped with a reducer, ------. In 2007, the world’s first counter-rotating mixed-flow turbine was successfully operated at **Dayuan in Shenzhen, and this type of turbine has since become the standard in the industry. About half a year later, many competitors also began to imitate the counter-rotating mixed-flow turbine. However, due to their insufficient technical capabilities, the reducers they produced had very high failure rates.” This turbine is a high specific speed Francis turbine; it was not in use for long before being replaced by the next generation of Francis turbines. High failure rate of reducers is one of the reasons for their elimination. 5. Shaft-driven Kaplan turbines (also known as tubular types, external type, with reducer, 2008–2009): The patent applied for on July 28, 2008, titled “Cooling tower driven by a turbine fan”, describes shaft-driven Kaplan turbines (also known as tubular types). Analysis of online information shows that turbines manufactured in this way were already put into use on-site in February 2009. This is one of the cooling tower turbine models that are widely used in practical applications at present. In the case of renovating an existing tower, there are few changes to the structures such as the equipment inside the ducts, the foundation, and the pipelines. 6. Ultra-low specific speed mixed-flow turbines (internal, direct-drive type) (2008–2009): Starting from the beginning of 2008, some manufacturers began to collaborate with universities on the research and development of turbines specifically designed for cooling towers, thus ushering in a promising period of integration between theoretical research and market demands, as well as between capital and knowledge. The main research institutions include North China University of Water Resources and Electric Power, Hohai University, Xi’an University of Technology, etc. Researchers have conducted in-depth theoretical analysis and experimental studies on the operating and control characteristics of cooling tower turbines, and found that compared to power generation turbines, they possess two key features: one is that they operate in series within pressurized water streams ； Rather, it features an ultra-low specific speed. Guided by theory, a completely new ultra-low specific speed mixed-flow turbine (built-in, direct-coupled type) specifically for cooling towers has been developed. **Announcement No. 33 of 2010 issued by the National Development and Reform Commission lists, under item 26 of the **Catalogue of Key Energy-Saving Technologies for Promotion (Third Batch)**, the technology titled \"Mixed-Flow Turbine Technology for Industrial Cooling Towers\" as a technology to be promoted for use in such cooling towers. It was subsequently included in the **List of Key Energy-Saving and Low-Carbon Technologies for Promotion** in 2014, 2015, and 2016. As mentioned in the aforementioned promotional text, under conditions where there is a 9–10 m head difference in a recirculating cooling water system, turbine generators can completely replace conventional fan motors. It should be noted that the announcement does not specify the entity that provided the technology; it only states that \"this technology has passed the evaluation for scientific and technological achievements in Nanjing and has been applied in industries such as petroleum, chemicals, steel, and light textiles.\" Energy-saving upgrades have been carried out on the cooling towers of over 300 enterprises across the country, achieving significant energy savings. ” However, several turbine manufacturers claim that their turbine technologies have been designated as **key energy-saving technology promotion projects by the National Development and Reform Commission. This model began to be put into actual use around 2009. If it is a renovation of an existing tower, there are many changes to the structures such as the equipment inside the ducts, the foundation, and the piping. 7. External horizontal-shaft water turbine (external, with gearbox; high specific speed; 2009). On February 26, 2009, an inventor in Shanghai filed a patent application titled “A transmission water turbine device for cooling towers and a cooling tower incorporating such a turbine,” which was the first to introduce the layout scheme of a turbine that is external and mounted horizontally in a mixed-flow (or axial-flow) configuration. The text does not specify whether the turbine is mixed-flow or axial-flow. Judging from the illustrations, it can be either mixed-flow or axial-flow. If it is an axial-flow type, then it’s essentially the same as the “2. External axial-flow cooling tower turbine at Xihua University”. In terms of mixed flow, it is novel. The patent specification explains the advantages of having a turbine mounted externally rather than internally, as follows: Inwardly mounted cooling tower turbines are installed in the middle of the air ducts, occupying ventilation space; to ensure sufficient ventilation area, the outer diameter of the turbine is restricted, which in turn limits the turbine’s output and hinders optimal design. This invention employs a turbine with a horizontal drive structure; it performs work outside the cooling tower body, the impeller can be enlarged as needed, and hydraulic parameters such as the inlet area are designed in an optimized manner, thereby reducing losses and improving efficiency. Analysis of online information shows that a certain company in Sichuan began manufacturing this type of mixed-flow cooling tower turbine in the first half of 2009, and it has since been put into actual operation. The appearance and layout of this machine are similar to those of the \"2. Xihua University External Axial Flow Cooling Tower Turbine (2005)\\", with the only difference being that one impeller is axial flow type while the other is mixed-flow type. I wonder if there is any connection between the two. On July 5, 2011, the company filed a patent application for this: “A power device for a cooling tower fan”. 8. Hybrid hydro-electric cooling tower turbines (2009–2012): As the use of water-driven fan cooling towers increased, it became more and more common for the fans to have insufficient rotation speeds after renovation, resulting in inadequate cooling performance. To address this situation and resolve the problem of insufficient turbine output, people have developed a hybrid hydro-electric cooling tower turbine. In addition to hydrodynamic force, the hybrid cooling tower turbine is also equipped with a motor drive; when the speed of the hydrodynamic fan alone is insufficient, the motor is activated to assist or replace the hydrodynamic force. This undoubtedly broadens the application range of the cooling tower turbine, making it possible to make use of energy more efficiently even with a lower head pressure in the cooling tower. The author believes this can be considered a significant improvement. The earliest patent in this area was filed on March 6, 2012, by a company in Dezhou, Shandong, for a patent titled \"Hybrid Water and Electric Cooling Tower System\". According to the website of a certain company, it began developing an energy-saving device for fans in hydro-hybrid cooling towers in 2009. By the end of 2009, the first-generation hydro-hybrid energy-saving fan designed specifically for cooling towers was introduced. After the product was stabilized and refined in 2010, the first-generation hybrid energy-saving fan was officially launched on the market. The product has now reached its fifth generation. The author believes that there is a key issue to address regarding dual-power systems: it is necessary to ensure that electric auxiliary drive serves merely to complement the hydraulic drive and act as a supplement, without overshadowing it or taking over its role. It’s like two people pulling a cart: one as the main puller and the other as the helper. First of all, the rope held by the main puller must be tight, with full effort applied ； If, on the other hand, the rope of the main mechanism is loose and the vehicle relies mainly on the helper to pull it, the purpose of saving energy is lost. Even more, if the helper exerts a strong pull at high speed, exceeding that of the main force, then wouldn’t the main force become an obstacle and a source of energy consumption? Therefore, when customers choose a dual-drive cooling tower turbine, they should ask the manufacturer to explain how a good match and organic integration between the water-driven force and the auxiliary driving force are ensured, how the distribution of these driving forces as well as their timely replenishment are controlled, and how it is possible to make maximum use of the water-driven force while providing the auxiliary driving force as needed. Think about it – this is not a simple or easy task; one needs to feel that the plan makes sense and that its implementation is guaranteed. To the best of my knowledge (these are merely my personal opinions and may not be entirely accurate), there are mainly two types of cooling tower turbines that are widely used nowadays and offer good performance. The first type is the “6. Mixed-flow turbine with extremely low specific speed (built-in, directly coupled type)”, as shown in the figure below. file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/msohtml1/01/clip_image002.gif The second type is “5. Shaft-extending tubular turbine (also known as pipe-type, external type with a speed reducer)”, as shown in the figure below. file:///C:/DOCUME~1/ADMINI~1/LOCALS~1/Temp/msohtml1/01/clip_image003.jpg Of course, both of these can be used in combination with hybrid drive systems. The above is a brief summary, prepared by the author based on the search and study of a large amount of information, of the development process of cooling tower turbines in chronological order, along with the characteristics of each type of turbine. Some types of turbines appear and coexist at different times. A certain company claims to have developed and optimized it to the eighth generation by now. The author did not introduce cooling tower turbines by generation in the article, as there is no clear standard or authoritative opinion on the matter. It’s also unclear exactly from which year onward the water-driven cooling tower market began to develop rapidly, turning into an industry of considerable scale, with manufacturers flocking to enter this field. Currently, there are dozens of companies engaged in the renovation of hydrodynamic fan cooling towers and the production of cooling tower turbines; among them are both manufacturers with strong capabilities and technical expertise, as well as copycat firms following suit. The turbines used are also diverse, but the quality varies greatly – there are both good ones and poor ones, as well as counterfeit products. Through years of promotion and application, there are both successful examples with excellent results and many lessons from failures. Through the process of natural selection, some counterfeit companies were also eliminated. In recent years, research on cooling tower turbines has become more in-depth, and understanding of them has grown more objective and rational. It is now recognized that energy-saving upgrades for water-driven fan cooling towers have their applicability and limitations, so such upgrades are no longer carried out impulsively. II. A brief discussion on the applicability (limitations) of water-driven fan cooling towers (to be continued) III. Comparison between energy-saving technologies for water-driven fan cooling towers and those for water pumps (to be continued)