A fan coil system

Abstract

This utility model provides a fan coil unit system, comprising: at least one fan coil unit assembly; a supply water temperature sensor and a return water temperature sensor are respectively installed on the chilled water supply line and the chilled water return line of each fan coil unit assembly; an electric regulating valve is installed on each chilled water supply line or chilled water return line; all supply water temperature sensors, return water temperature sensors, and electric regulating valves are respectively connected to a thermostat. The fan coil unit system provided by this application can collect temperature data in real time through the supply water temperature sensor and the return water temperature sensor. The thermostat adjusts the indoor temperature based on the temperature difference between the supply and return water, thereby achieving precise indoor temperature regulation, reducing temperature fluctuations, and improving indoor comfort.

Description

Technical Field

[0001] This utility model relates to the field of heating, ventilation and air conditioning technology, and specifically to a fan coil system. Background Technology

[0002] In the field of building environmental control, fan coil units play an indispensable role as an important air conditioning device. They are precisely assembled from key components such as fans, heat exchangers, and filters to form a complete system. With their advantages of compact structure, flexible installation, and good regulation performance, fan coil systems are widely used in public buildings (such as shopping malls, office buildings, and hotels) and data centers, where high indoor environmental requirements exist.

[0003] The core control objective of a fan coil unit system is to achieve precise indoor temperature regulation to meet the usage needs of different locations. It adjusts the on / off state of the chilled water electric valve based on the return air temperature. Specifically, the system monitors the return air temperature in real time through sensors and feeds this temperature signal back to the controller. The controller compares and analyzes the preset temperature setpoint with the actual return air temperature, and then controls the opening or closing degree of the chilled water electric valve, thereby adjusting the chilled water flow rate into the heat exchanger, thus changing the heat exchanger's heat transfer capacity, and ultimately achieving indoor temperature regulation.

[0004] However, with the increasing demands for building energy conservation and people's growing pursuit of indoor environmental comfort, the existing fan coil systems are not accurate enough in regulating indoor temperature. Utility Model Content

[0005] This invention provides a fan coil system to address the shortcomings of existing fan coil systems in accurately regulating indoor temperature.

[0006] A fan coil system, comprising:

[0007] At least one fan coil unit is provided with a supply water temperature sensor and a return water temperature sensor respectively on the chilled water supply line and the chilled water return line of each fan coil unit.

[0008] An electric regulating valve is installed on each of the chilled water supply pipes or chilled water return pipes;

[0009] All water supply temperature sensors, return water temperature sensors, and electric regulating valves are connected to the thermostat.

[0010] Furthermore, in the fan coil system described above, the electric regulating valve is installed on the chilled water return pipe;

[0011] Its valve body is connected to the chilled water return pipeline via a flange, and a manual operating handle is provided on the valve body for manual adjustment when the electric adjustment fails.

[0012] Furthermore, in the fan coil system described above, the opening resolution of the electric regulating valve is not less than 1%.

[0013] Furthermore, in the fan coil system described above, the water supply temperature sensor is installed on a straight pipe section 0.5m upstream of the coil inlet, at a 45° angle to the water flow direction.

[0014] Furthermore, in the fan coil system described above, a return air temperature sensor is installed at the return air inlet of each fan coil unit;

[0015] The return air temperature sensor is fixed to the side wall of the return air inlet by a metal bracket, and its probe extends into the return air flow; all the return air temperature sensors are connected to the temperature controller.

[0016] Furthermore, in the fan coil system described above, an indoor temperature sensor is installed in the room where the fan coil unit is equipped.

[0017] The indoor temperature sensor is fixed to the indoor wall by suction cup or screw, and its height is between 1.5 meters and 2 meters from the ground;

[0018] The indoor temperature sensor is connected to the thermostat.

[0019] Furthermore, in the fan coil system described above, the fan, heat exchanger, and filter are connected in sequence by pipes and connectors and encapsulated in a metal casing, which is provided with an inspection door.

[0020] Furthermore, in the fan coil system described above, the heat exchanger adopts a copper tube and aluminum fin structure, and the copper tube and aluminum fin are tightly connected by a tube expansion process; both ends of the heat exchanger are connected to the chilled water supply pipeline and the chilled water return pipeline through flanges.

[0021] Furthermore, in the fan coil system described above, the filter is a detachable plate filter, and the filter is fixed to the air inlet of the fan coil assembly by a slide rail or snap-fit ​​structure.

[0022] The fan coil unit system provided by this utility model can collect temperature in real time through supply water temperature sensors and return water temperature sensors. The thermostat adjusts the indoor temperature by the temperature difference between the supply and return water, thereby achieving the purpose of accurately adjusting the indoor temperature, reducing temperature fluctuations, and improving indoor comfort. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the fan coil unit structure in this application;

[0024] Figure 2 This is a schematic diagram of the fan coil unit system structure of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0026] Figure 1 This is a schematic diagram of the fan coil unit structure in this application. Figure 2 This is a schematic diagram of the fan coil unit system structure of this application, as shown below. Figure 1 , Figure 2 As shown, the fan coil system provided in this application includes: at least one fan coil unit 1, with a supply water temperature sensor 2 and a return water temperature sensor 3 respectively installed on the chilled water supply line 11 and the chilled water return line 12 of each fan coil unit 1; an electric regulating valve 4 is installed on each chilled water supply line 11 or chilled water return line 12; and all the supply water temperature sensors 2, return water temperature sensors 3, and electric regulating valves 4 are respectively connected to a thermostat 6.

[0027] Specifically, each fan coil unit is equipped with a supply water temperature sensor and a return water temperature sensor on its chilled water supply and return lines, respectively. These sensors monitor the supply and return temperatures of the chilled water in real time. The sensors transmit the collected temperature data to the thermostat in real time. The thermostat receives and processes the data from the sensors, including calculating the supply and return water temperature difference, comparing this return water temperature difference with a preset temperature difference value, and determining the opening degree of the electric regulating valve based on the comparison result. The thermostat then sends an opening control signal to the electric regulating valve to open it according to the required opening degree, thereby changing the chilled water flow rate. The change in chilled water flow rate affects the heat exchanger's heat exchange capacity, thus changing the indoor temperature and ultimately achieving the goal of controlling the indoor temperature.

[0028] Furthermore, if a thermostat can only control one fan coil unit, the return air temperature in different areas of a large room will be uneven. An independently controlled thermostat can only adjust the temperature based on its local area and cannot coordinate the operation of fan coil units in other areas, resulting in uneven overall temperature, affecting comfort, and causing some equipment to operate at high loads for extended periods, leading to significant energy waste. Therefore, it is necessary to implement coordinated control of fan coil units within a given area. This application incorporates at least two fan coil unit assemblies in a room. By connecting all fan coil unit assemblies in the room to a thermostat, the thermostat achieves group control functionality. Thus, the thermostat can manage multiple fan coil units simultaneously, enabling coordinated control. By integrating data from all fan coil units in the area, the thermostat can uniformly adjust the valve opening and fan speed of all fan coil units based on the average temperature of the area, thereby avoiding localized overcooling or overheating and improving overall operating efficiency. This group control method helps balance the distribution of cooling capacity within the area, reducing energy waste and achieving energy-saving effects. Furthermore, this application centrally manages multiple fan coil units using a single thermostat. When a new fan coil unit is added, no additional thermostat is required; it is automatically connected to the group control network via its device number. This centralized management approach reduces system deployment costs and management complexity, while also minimizing energy waste that may result from decentralized device management, further enhancing energy efficiency.

[0029] The fan coil unit system provided in this application can collect temperature data in real time through supply water temperature sensors and return water temperature sensors. The thermostat adjusts the indoor temperature by the temperature difference between the supply and return water, thereby achieving the purpose of accurately regulating the indoor temperature, reducing temperature fluctuations, and improving indoor comfort.

[0030] It should be clarified that the core innovation of the thermostat program in this application, which adjusts the opening of the electric regulating valve based on the supply and return water temperature difference, lies not in the control logic itself, but in the combination of this logic with other technical features (such as multi-sensor collaborative data acquisition and adaptive dynamic adjustment of temperature difference thresholds). Regarding the single program module of calculating and comparing the supply and return water temperature difference and adjusting the valve opening, it is a conventional technical measure that can be directly derived and implemented by a person skilled in the art based on existing technology, and does not possess the level of inventiveness required by the Patent Examination Guidelines. Although the program module itself is conventional technology, this application achieves the technical effect of precisely adjusting indoor temperature and improving indoor comfort by combining the thermostat with supply and return water temperature sensors and the electric regulating valve.

[0031] Furthermore, the electric regulating valve 4 is installed on the chilled water return pipe 12; its valve body is connected to the chilled water return pipe through a flange, and a manual operating handle is provided on the valve body for manual adjustment when the electric regulation fails.

[0032] Specifically, chilled water first passes through the supply water pipeline before entering the fan coil unit for heat exchange. If the electric regulating valve is located in the supply water pipeline, there is a long transmission distance and time lag between the opening of the electric regulating valve and its impact on the cooling effect of the fan coil unit. For example, when the indoor load changes and the chilled water flow needs to be adjusted, because there is already a large amount of chilled water flowing in the supply water pipeline, the new flow rate takes some time to reach the fan coil unit after the electric regulating valve is adjusted. This results in a slow temperature regulation response, failing to meet the indoor temperature change requirements in a timely manner, exacerbating indoor temperature fluctuations, and thus reducing comfort. Compared with the return water pipeline, it cannot reflect the actual heat exchange status of the fan coil unit and changes in indoor load in a timely and accurate manner. Therefore, this application, by placing the electric regulating valve in the chilled water return water pipeline, can effectively improve the comfort of indoor temperature regulation.

[0033] Furthermore, this application connects the electric regulating valve to the chilled water return pipeline via a flange. This connection method has a high degree of standardization, the installation process is relatively simple, and the valve can be quickly and accurately positioned and fixed, reducing installation time and labor costs. At the same time, the flange connection provides good sealing, effectively preventing chilled water leakage and ensuring stable system operation. In later maintenance, if the electric regulating valve needs to be inspected or replaced, the flange connection also facilitates disassembly and reinstallation, reducing maintenance difficulty and costs.

[0034] The inclusion of a manual operating handle provides a reliable redundant operating method for the system. Specifically, in emergency situations where the electric regulator fails, such as power outages, controller malfunctions, or electrical faults in the electric regulating valve itself, operators can directly control the opening of the electric regulating valve using the manual operating handle. This regulates the chilled water flow, ensuring the fan coil system can still regulate the indoor temperature to a certain extent, maintaining basic indoor comfort and preventing uncontrolled temperature fluctuations due to electric regulator failure. This ensures continuous system operation and reliability. This manual operation redundancy design effectively reduces the risk of the entire fan coil system failing due to electric regulator problems, enhances the system's ability to cope with sudden failures, and enables the system to maintain a certain level of operational capability under various complex operating conditions, providing users with more reliable indoor environmental regulation. Therefore, this application effectively improves the system's reliability by incorporating a manual operating handle.

[0035] Furthermore, the opening resolution of the electric regulating valve in this application is not less than 1%.

[0036] Specifically, an opening resolution of at least 1% means that the electric regulating valve can adjust its opening by extremely small increments, thereby achieving precise fine-tuning of the chilled water flow rate. In indoor environmental control, different locations have varying temperature requirements, and the human body is highly sensitive to temperature changes. A high-resolution electric regulating valve can promptly and accurately adjust the chilled water flow rate based on minute changes in the supply and return water temperature difference, thus stabilizing the indoor temperature near the set value and preventing large temperature fluctuations, providing users with a more comfortable indoor environment. Furthermore, for locations with extremely high requirements for indoor temperature accuracy, such as data centers, laboratories, and museums, even minor temperature changes can have a significant impact on equipment operation, experimental results, or the preservation of exhibits. Electric regulating valves with an opening resolution of at least 1% can meet the precise temperature control needs of these locations, ensuring that the indoor environment remains stable and suitable, and guaranteeing the safety and normal operation of related equipment, experiments, or exhibits.

[0037] Furthermore, in traditional fan coil systems, if the electric regulating valve's opening accuracy is insufficient, it may over-adjust or under-adjust when responding to temperature changes. This can cause the system to oscillate repeatedly around the target temperature, affecting system stability and indoor comfort. High-resolution electric regulating valves, however, can more precisely match chilled water flow to indoor heat load demands, resulting in smoother system regulation, reduced temperature fluctuations and system oscillations, and improved overall system stability. Moreover, because high-resolution electric regulating valves can more accurately control chilled water flow, they avoid the impact and wear caused by over-adjustment or frequent adjustments to heat exchangers, pumps, and other equipment. This reduces equipment operating load and the risk of failure, thereby extending the service life of the entire fan coil system and reducing equipment maintenance and replacement costs.

[0038] Furthermore, in a building environment, indoor heat load dynamically changes with factors such as the number of people, equipment operating status, and outdoor weather conditions. Electric regulating valves with an opening resolution of at least 1% can adjust the chilled water flow rate in real time and accurately according to changes in indoor heat load, ensuring the system always operates under optimal conditions and avoiding energy waste caused by excessive or insufficient flow. For example, when the indoor heat load is low, the electric regulating valve can be fine-tuned to a smaller opening, reducing chilled water flow, lowering the energy consumption of the water pump and chiller unit, and achieving energy-saving operation.

[0039] Furthermore, in the system provided in this application, the water supply temperature sensor is installed on a straight pipe section 0.5m upstream of the coil inlet, and at a 45° angle to the water flow direction.

[0040] Specifically, fluids easily form eddies (vortices) and turbulence (irregular flow) at bends, valves, pump outlets, etc., leading to uneven local temperature distribution. If the water supply temperature sensor is installed in the eddy region, the measured temperature may be lower than the actual water temperature (because the eddy center has a high flow velocity, high heat transfer coefficient, and strong cooling effect). This application inserts the water supply temperature sensor at a 45° angle, allowing the sensor probe to avoid the core area of ​​the eddy and measure the average temperature of the mainstream area, thereby reducing local low-temperature deviation. In addition, when fluid flows in a pipe, the flow velocity near the pipe wall is lower than the central flow velocity (velocity gradient), resulting in uneven temperature distribution. If the sensor is installed in a straight pipe section that is too short (e.g., <0.3m), it may measure false high temperatures (higher fluid temperature near the pipe wall) because the velocity gradient is not fully developed. A length of 0.5m ensures that the fluid is fully developed (velocity gradient is stable), avoiding the measurement of high pipe wall temperatures, thereby improving the accuracy of the water supply temperature and ultimately achieving accurate and comfortable indoor temperature regulation.

[0041] Furthermore, a return air temperature sensor is installed at the return air inlet of each fan coil unit; the return air temperature sensor is fixed to the side wall of the return air inlet by a metal bracket, and its probe extends into the return airflow; all return air temperature sensors are connected to the thermostat.

[0042] Specifically, fan coil units regulate indoor temperature through air circulation. The return air is air that has undergone indoor heat exchange, and its temperature directly reflects the current indoor heat load and the cooling / heating effect of the equipment.

[0043] This application uses a thermostat that connects to a supply water temperature sensor, a return water temperature sensor, an electric regulating valve, and a return air temperature sensor. By constructing a multi-parameter collaborative sensing and dynamic adjustment closed loop, it achieves precise control and energy efficiency optimization of the fan coil system.

[0044] Furthermore, this application extends the sensor probe into the return airflow, enabling real-time capture of airflow temperature changes. This avoids data distortion caused by improper sensor installation (such as proximity to walls or air vents), ensuring the thermostat obtains accurate environmental parameters. For example, in a conference room setting, if the sensor is not inserted into the return airflow, airflow stratification may cause temperature detection lag. Precise installation can shorten system response time by more than 30%, preventing indoor overheating. Additionally, the metal bracket in this application rigidly secures the sensor, preventing displacement or damage due to fan vibration or airflow impact, thus ensuring continuous data acquisition.

[0045] In one embodiment of this application, the metal bracket may be made of galvanized or stainless steel to adapt to the humid environment of the air conditioning system, thereby extending its service life by more than 50% compared to the plastic bracket.

[0046] It should be noted that the thermostat in this application uses PID or fuzzy control to electrically regulate the valve opening. Its core algorithms (such as parameter tuning for proportional gain Kp, integral time Ti, and derivative time Td) are publicly available industry technologies. Engineers can calibrate these parameters based on the "HVAC Automatic Control Technology Manual" or equipment manufacturer's technical documents, combined with system characteristics (such as coil water capacity and hydraulic resistance). Weighted calculations or fuzzy inference of signals such as supply water temperature, return water temperature, and return air temperature essentially constitute a "multi-input single-output" control system design. For example, the weighted average method: return air temperature weight 60%, return water temperature weight 30%, and supply water temperature weight 10%. If the "return air temperature is too high" and the "supply and return water temperature difference is too small," then the "valve opening is increased and the pump frequency is reduced." Such algorithms have mature applications in industrial control fields (such as boiler combustion control and air conditioning water system balancing). This application does not propose any new control theories (such as novel algorithms to replace PID) or mathematical models (such as dynamic thermodynamic prediction models). Therefore, the development of the temperature controller program in this application only involves conventional techniques in the field, such as PID parameter tuning and data filtering algorithms.

[0047] Furthermore, an indoor temperature sensor is installed in the room equipped with fan coil unit components; the indoor temperature sensor is fixed to the indoor wall by suction cup or screw, and its height is between 1.5 meters and 2 meters from the ground; the indoor temperature sensor is connected to the thermostat.

[0048] Specifically, the return air temperature sensor reflects the air temperature after being processed by the fan coil unit, while the indoor temperature sensor reflects the actual temperature perceived by people. Combining the two can eliminate local temperature differences caused by uneven airflow distribution. For example, in a large space, if only the return air temperature is relied upon for regulation, the temperature in the activity area may be too high due to the sinking of cold air. The indoor temperature sensor can provide timely feedback and correction.

[0049] Furthermore, since indoor human activity is mainly concentrated within a height range of 1.5-2 meters above the ground, sensors installed at this height can accurately capture temperature changes in the activity area. This avoids the effects of cold radiation or heat accumulation from the ground due to installation too low (e.g., near the ground), or direct interference from air conditioning airflow due to installation too high (e.g., near the ceiling). Suction cup mounting is suitable for temporary installations or rental locations, eliminating the need for drilling and avoiding damage to walls; screw mounting is suitable for long-term stable installations, offering stronger load-bearing capacity and superior vibration resistance. Both mounting methods support quick disassembly, facilitating periodic sensor calibration or battery replacement (for wireless models), reducing maintenance time by more than 80% compared to embedded installations.

[0050] Furthermore, in the system provided in this application, the fan, heat exchanger, and filter are connected in sequence by pipes and connectors and encapsulated in a metal casing, which is provided with an access door.

[0051] The system provided in this application, unlike traditional distributed layouts which require separate installation space for fans, heat exchangers, and filters, achieves a 30%-50% reduction in equipment volume through integrated packaging, effectively minimizing installation footprint. Furthermore, by sequentially connecting the fan, heat exchanger, and filter via pipes and connectors and encapsulating them within a single metal casing, the complex on-site piping welding is avoided, reducing installation time. Additionally, the access door covers the three core components—fan, heat exchanger, and filter—allowing for visual inspection (e.g., fan belt wear, heat exchanger frost, filter dust accumulation) without disassembling the casing, significantly shortening troubleshooting time.

[0052] Furthermore, in the system provided in this application, the heat exchanger adopts a copper tube and aluminum fin structure, and the copper tube and aluminum fin are tightly connected by a tube expansion process; both ends of the heat exchanger are connected to the chilled water supply pipeline and the chilled water return pipeline through flanges.

[0053] Specifically, due to the high thermal conductivity of copper and the lightweight and large specific surface area of ​​aluminum, this application adopts a copper tube and aluminum fin structure, which can effectively improve heat exchange efficiency. Furthermore, the copper tube and aluminum fin are tightly connected through a tube expansion process, which can eliminate contact thermal resistance and improve heat transfer efficiency by more than 50%.

[0054] Furthermore, in the system provided in this application, the filter is a detachable plate filter, and the filter is fixed to the air inlet of the fan coil unit by a slide rail or snap-fit ​​structure.

[0055] Specifically, when the filter is fixed to the air inlet of the fan coil unit using a slide rail, two parallel galvanized steel guide rails are pre-embedded in the inner wall of the air inlet. The PVC slider on the edge of the filter is embedded in the groove of the guide rail to achieve "push-in and lock", and the installation can be completed with one hand.

[0056] When the filter is fixed to the air inlet of the fan coil unit using a snap-fit ​​structure, ABS engineering plastic snap-fits (with anti-detachment hooks) are installed at the four corners of the filter frame, forming a "four-point force" lock with the pre-embedded slot (10mm deep) in the air inlet. A push-type unlock button (3mm pressing stroke) is set on the top of the snap-fit, which allows maintenance personnel to unlock with one hand without tools, reducing the disassembly and assembly time to 10 seconds per time.

[0057] The system provided in this application, through the combination of a detachable plate filter and a slide rail / clip fastener, allows for quick and easy replacement of the system without the need for tools, thus reducing labor and time costs.

[0058] Furthermore, in the system provided in this application, the supply water temperature sensor, return water temperature sensor, return air temperature sensor, indoor temperature sensor, and electric regulating valve are all connected to the electric regulating valve via wireless communication (Bluetooth, Wi-Fi, Internet of Things).

[0059] The system provided in this application uses wireless communication to connect the supply water temperature sensor, return water temperature sensor, return air temperature sensor, indoor temperature sensor, and electric regulating valve. It has the advantages of convenient installation, easy maintenance, high flexibility, high data transmission efficiency, and strong intelligent integration capability.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A fan-coil system, characterized by, include: At least one fan coil unit is provided with a supply water temperature sensor and a return water temperature sensor respectively on the chilled water supply line and the chilled water return line of each fan coil unit. An electric regulating valve is installed on each of the chilled water supply pipes or chilled water return pipes; All water supply temperature sensors, return water temperature sensors, and electric regulating valves are connected to the thermostat.

2. The fan coil system according to claim 1, characterized in that, The electric regulating valve is installed on the chilled water return pipe; Its valve body is connected to the chilled water return pipeline via a flange, and a manual operating handle is provided on the valve body for manual adjustment when the electric adjustment fails.

3. The fan coil system according to claim 2, characterized in that, The opening resolution of the electric regulating valve is not less than 1%.

4. The fan coil system according to claim 2, characterized in that, The water supply temperature sensor is installed on a straight pipe section 0.5m upstream of the coil inlet, at a 45° angle to the water flow direction.

5. The fan coil system according to claim 1, characterized in that, A return air temperature sensor is installed at the return air inlet of each of the fan coil units; The return air temperature sensor is fixed to the side wall of the return air inlet by a metal bracket, and its probe extends into the return air flow; all the return air temperature sensors are connected to the thermostat.

6. The fan coil system according to claim 5, characterized in that, An indoor temperature sensor is installed in the room equipped with the fan coil unit; the indoor temperature sensor is fixed to the indoor wall by suction cup or screw, and its height is between 1.5 meters and 2 meters from the ground. The indoor temperature sensor is connected to the thermostat.

7. The fan coil system according to any one of claims 1-6, characterized in that, The fan, heat exchanger, and filter are connected in sequence by pipes and connectors and enclosed in a metal casing, which is equipped with an inspection door.

8. The fan coil system according to claim 7, characterized in that, The heat exchanger adopts a copper tube and aluminum fin structure, and the copper tube and aluminum fin are tightly connected by a tube expansion process; the two ends of the heat exchanger are connected to the chilled water supply pipeline and the chilled water return pipeline through flanges.

9. The fan coil system according to claim 7, characterized in that, The filter is a detachable plate filter, and it is fixed to the air inlet of the fan coil unit by a slide rail or snap-fit ​​structure.

10. The fan coil system according to claim 6, characterized in that, The water supply temperature sensor, return water temperature sensor, return air temperature sensor, indoor temperature sensor, and electric regulating valve are all connected to the electric regulating valve via wireless communication.

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