Abstract: This paper presents an in-depth analysis of failure cases related to circulating pumps in central air conditioning systems. By examining real-world engineering problems, it highlights the critical importance of selecting the pump head appropriately and provides practical methods for doing so. The study aims to offer valuable insights for HVAC designers, emphasizing that proper pump selection is essential for system efficiency, cost-effectiveness, and long-term reliability. 1. Introduction 2. Theoretical Background 3. Case Studies Case 2: Another project involved a regional cooling and heating station serving multiple buildings. A circulating pump failed to provide sufficient flow, causing the chiller to shut down. Investigation showed that the pump had insufficient head, and the system resistance was higher than expected. Additionally, a clogged filter contributed to poor performance. After replacing the filter and recalculating the hydraulic system, the pump was replaced with a more appropriate model, restoring normal operation and avoiding further losses. 4. Conclusion Conical Twin Screw And Barrel,Plastic Sheet Machine Screw And Barrel,Extruder Screw And Barrel,Plastic Sheet Machine Zhejiang Guangming Plastics Machinery Co.,Ltd. , https://www.gmscrews.com
Keywords: Central air conditioning; Pump head; Proper selection; System resistance; Hydraulic calculation
Abstract: This article explores engineering failures caused by improper selection of the pump head in central air conditioning systems. It emphasizes the significance of a rational approach to pump selection and outlines several effective strategies. The findings are intended to guide HVAC engineers in making more informed decisions during system design.
Keywords: Central air conditioning; Water pump head; Proper selection
In central air conditioning systems, the circulating pump plays a crucial role in delivering chilled water in summer and hot water in winter to terminal devices. The correct selection of the pump head is based on accurate calculations of system flow and resistance. However, in many real projects, engineers often rely on experience rather than following standard design procedures outlined in HVAC manuals. This can lead to underperforming or inefficient systems, increased operating costs, or even complete system failure. These issues have raised serious concerns among air conditioning designers.
The required water flow in an air conditioning system is determined by the temperature difference between the supply and return water, while the system resistance is calculated through hydraulic analysis. A properly selected pump should operate within its high-efficiency range, with the working point being the intersection of the pump curve and the system characteristic curve. However, in practice, two common issues arise: one where the pump head is unnecessarily high, and another where it is too low. Both situations can lead to inefficiencies, excessive energy consumption, or operational instability.
Case 1: In a single-story high-rise building, the initial pump selection resulted in an oversized pump head. During commissioning, the motor current was excessively high, and abnormal vibrations and noises were observed. Further analysis revealed that the actual system resistance was much lower than estimated, leading to unnecessary pressure loss through valve throttling. The solution involved replacing the pump with a more suitable model, which significantly improved energy efficiency and system performance.
1) While selecting a circulating pump may seem straightforward, it requires careful attention to both theoretical calculations and practical experience.
2) The pump head should not be chosen solely based on the assumption that "higher is better." Instead, economic efficiency and system compatibility must be considered.
3) With rapid technological advancements in air conditioning equipment, designers must remain vigilant and thoroughly evaluate new products before implementation.
4) Proper pump selection is not only a technical challenge but also a key factor in ensuring the long-term success and sustainability of any central air conditioning system.