A type of return air reheat fan coil unit

Abstract

This utility model discloses a reheat fan coil unit, comprising a fan, a heat exchanger, a primary return air box, a secondary return air box, a fresh air inlet, a primary return air outlet, a secondary return air outlet, a secondary return air duct, and an air supply outlet. The primary return air box has a fresh air inlet and a primary return air outlet; the secondary return air box has a secondary return air outlet, a secondary return air duct, and an air supply outlet. The primary return air box is connected to the heat exchanger inlet, and the heat exchanger outlet is connected to the secondary return air box. The fan includes a volute, a fan impeller, and a motor. Its air intake is connected to the secondary return air box, and its air outlet is connected to the secondary return air box's air supply outlet. The secondary return air duct is installed in the secondary return air box, with its lower air intake connected to the secondary return air outlet and its upper air outlet connected to the secondary return air box shell. The upper air outlet is higher than the fan motor, housing the fan motor within it. During winter operation, low-temperature indoor air enters the secondary return air duct, cooling the motor, preventing motor burnout, and extending motor life.

Description

Technical Field

[0001] This utility model belongs to the field of ventilation and air conditioning, and specifically relates to a return air reheat type fan coil unit. Background Technology

[0002] Chinese patent “Independent Temperature and Humidity Control Fan Coil Unit” (application number 202411190091X) discloses a return air reheat type fan coil unit. Its fan is placed at the front end of the heat exchanger. However, in winter, after the air is heated by the heat exchanger, it has to flow through the fan motor. The high temperature air is not conducive to the heat dissipation of the motor, which can easily cause it to burn out and affect the life of the motor. Summary of the Invention

[0003] The purpose of this invention is to provide a fan coil unit that avoids the hot air heated by the heat exchanger in winter from flowing through the return air reheating of the fan motor. This is beneficial for motor heat dissipation, prevents motor burnout, and improves motor life.

[0004] The solution of this utility model is: a return-air reheat type fan coil unit, which includes a fan, a heat exchanger, a primary return air box, a secondary return air box, a fresh air inlet, a primary return air inlet, a secondary return air inlet, a secondary return air duct, and an air supply outlet. The primary return air box has a fresh air inlet and a primary return air inlet; the secondary return air box has a fan, a secondary return air inlet, a secondary return air duct, and an air supply outlet. The primary return air box is connected to the heat exchanger inlet, and the heat exchanger outlet is connected to the secondary return air box. The fan is installed in the secondary return air box and includes a volute, a fan wheel, and a motor. The air outlet is connected to the secondary return air box, and the air outlet is connected to the air supply outlet of the secondary return air box. The secondary return air duct is installed in the secondary return air box. The lower air inlet is connected to the secondary return air outlet, and the upper air outlet is connected to the secondary return air box and connected to the shell of the secondary return air box. The upper air outlet is higher than the fan motor, and the fan motor is fitted inside it. All the air entering the secondary return air outlet flows through the fan motor and then enters the secondary return air box. The fan is a variable speed fan. The fresh air inlet, primary return air inlet, and secondary return air inlet are adjustable air outlets. The heat exchanger is connected to the air conditioning chilled / hot water or refrigerant.

[0005] When the air is cooled in summer, the fresh air inlet, primary return air inlet, and secondary return air inlet are all open. The fan is started, and the refrigerant in the heat exchanger is connected. Under the suction of the fan, the indoor primary return air enters the primary return air box through the primary return air inlet, and the outdoor fresh air enters the primary return air box through the fresh air inlet. After mixing, the air is sent to the heat exchanger to cool and dehumidify it to the dew point. Then it is sent to the secondary return air box. Another part of the indoor return air with a higher temperature enters the secondary return air duct through the secondary return air inlet under the suction of the fan. After flowing through the fan motor, it enters the secondary return air box, mixes with the low-temperature air treated by the heat exchanger, is reheated and heated to the design supply air temperature, and is finally sent to the air-conditioned room by the fan through the supply air outlet.

[0006] During winter heating operation, the fresh air inlet and primary return air inlet are fully open, while the secondary return air inlet is slightly open. The fan is started, and the heat medium in the heat exchanger is connected. Driven by the fan, indoor primary return air enters the primary return air box through the primary return air inlet, and outdoor fresh air enters through the fresh air inlet. After mixing, the air is sent to the heat exchanger for heating, and then to the secondary return air box. Because the secondary return air inlet is slightly open, a small amount of cooler indoor return air is drawn in by the fan and enters the secondary return air duct. This air flows past the fan motor, cooling it, and then enters the secondary return air box, mixing with the heated air processed by the heat exchanger to reach the designed supply air temperature. Finally, the air is delivered to the air-conditioned room by the fan through the supply air outlet. The small amount of cool indoor return air entering the secondary return air duct prevents the entry of hot air, ensuring motor cooling and minimizing the impact on the supply air temperature. Attached Figure Description

[0007] Figure 1 This is a structural diagram of a reheat fan coil unit.

[0008] Figure 2 yes Figure 1 AA section Figure 1

[0009] Figure 3 yes Figure 1 AA section Figure 2

[0010] Explanation of reference numerals in the attached figures:

[0011] 1. Fresh air inlet, 2. Primary return air inlet, 3. Primary return air box, 4. Heat exchanger, 5. Secondary return air box, 6. Air supply plate, 7. Air supply outlet, 8. Secondary return air inlet, 9. Secondary return air duct, 10. Fan casing, 11. Fan motor, 12. Refrigerant pipe, 13. Duct notch, 14. Motor shaft, 15. Motor mounting bracket, 16. Filter screen, 17. Top cover plate, 18. Ventilation hole. Detailed Implementation

[0012] Figure 1 , 2A reheat fan coil unit includes a fan, a heat exchanger 4, a primary return air box 3, a secondary return air box 5, a fresh air inlet 1, a primary return air outlet 2, a secondary return air outlet 8, a secondary return air duct 9, and an air supply outlet 7. The primary return air box 3 has a fresh air inlet 1 and a primary return air outlet 2, while the secondary return air box 5 has a secondary return air outlet 8, a secondary return air duct 9, and an air supply outlet 7. The primary return air box 3 is connected to the air inlet of the heat exchanger 4, and the air outlet of the heat exchanger 4 is connected to the secondary return air box 5. The fan is installed in the secondary return air box 5 and includes a fan casing 10, a fan impeller, and a fan motor 11. Its air intake is connected to the secondary return air box 5, and its air outlet is connected to... The air outlet 7 and secondary return air duct 9 of the secondary return air box 5 are installed in the secondary return air box 5. The lower air inlet is connected to the secondary return air outlet 8, and the upper air outlet is connected to the secondary return air box 5 and connected to the shell of the secondary return air box 5. The upper air outlet is higher than the fan motor 11, and the fan motor 11 is fitted inside it. All the air entering the secondary return air outlet 8 flows through the fan motor 11 and then enters the secondary return air box 5, thus ensuring that the fan motor 11 is fully cooled. The fan is a variable speed fan with three speed settings. The fresh air outlet 1, the primary return air outlet 2, and the secondary return air outlet 8 are adjustable electric or manual air outlets. The heat exchanger 4 is connected to the air conditioner's hot or cold water or refrigerant. The secondary return air box 5 has an air supply plate 6 with an air supply outlet 7 connected to the fan outlet and the room's air supply duct. The diagram shows a single motor with double volutes. The fan motor 11 is a coaxial motor, fixed to the air supply plate 6 via a motor mounting bracket 15. Alternatively, a single motor with a single volute or a single motor with three volutes can be used. The secondary return air duct 9 has a duct notch 13. During installation, the duct notch 13 passes through the motor shaft 14, fixing the secondary return air duct 9 to the air supply plate 6. Through calculation and adjustment of the fresh air inlet 1, primary return air inlet 2, and secondary return air inlet 8 during actual operation, the airflow balance of each inlet is ensured to meet air conditioning requirements. The area of ​​the secondary return air inlet 8 should ideally be between 20% and 50% of the sum of the areas of the fresh air inlet 1 and the primary return air inlet 2. A smaller area can be adjusted during winter operation. Filters are installed at the fresh air inlet 1, primary return air inlet 2, and secondary return air inlet 8.

[0013] When the air is cooled in summer, the fresh air inlet 1, the primary return air inlet 2, and the secondary return air inlet 8 are all fully open. The fan is started, and the refrigerant in the heat exchanger 4 is connected. Under the suction of the fan, the indoor primary return air enters the primary return air box 3 through the primary return air inlet 2, and the outdoor fresh air enters the primary return air box 3 through the fresh air inlet 1. After mixing, the air is sent to the heat exchanger 4 to cool and dehumidify the air to the dew point state, and then sent to the secondary return air box 5. Another part of the indoor return air with a higher temperature enters the secondary return air duct 9 through the secondary return air inlet 8 under the suction of the fan. After flowing through the fan motor 11, it enters the secondary return air box 5, mixes with the low temperature air treated by the heat exchanger 4, is reheated and heated to the design supply air temperature, and is finally sent to the air-conditioned room by the fan through the supply air outlet 7. Since the indoor secondary return air temperature is about 26 degrees, it is beneficial to the heat dissipation of the fan motor 11 when it flows through the fan motor 11.

[0014] During winter heating operation, the fresh air inlet 1 and the primary return air inlet 2 are fully open, while the secondary return air inlet 8 is slightly open. The fan is started, and the heat medium in the heat exchanger 4 is connected. Under the suction of the fan, the indoor primary return air enters the primary return air box 3 through the primary return air inlet 2, and the outdoor fresh air enters through the fresh air inlet 1. After mixing, the air is sent to the heat exchanger 4 to heat the air, and then sent to the secondary return air box 5. Because the secondary return air inlet 8 is slightly open, a small amount of cooler indoor return air is drawn in by the fan and enters the secondary return air duct 9 through the secondary return air inlet 8. It flows through the fan motor 11, cooling the motor, and then enters the secondary return air box 5, mixing with the hot air treated by the heat exchanger 4 to reach the designed supply air temperature. Finally, it is sent to the air-conditioned room by the fan through the supply air outlet 7. Because a small amount of cool indoor return air enters the secondary return air duct 9, it prevents the entry of hot air, ensuring the heat dissipation of the fan motor 11, while having a minimal impact on the supply air temperature.

[0015] Figure 3 In this design, an upper cover plate 17 is added to the upper air outlet of the secondary return air duct 9, and a ventilation hole 18 is opened on the upper part of the secondary return air duct 9. The secondary return air enters the secondary return air box 5 through the ventilation hole 18 and the air duct opening 13. Due to the addition of the upper cover plate 17, hot air can be effectively prevented from entering the secondary return air duct 9, which is beneficial to the heat dissipation of the fan motor 11.

[0016] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A reheat fan coil unit, comprising a fan, a heat exchanger, a primary return air box, a secondary return air box, a fresh air inlet, a primary return air outlet, a secondary return air outlet, a secondary return air duct, and an air supply outlet, characterized in that, The primary return air box has a fresh air inlet and a primary return air inlet. The secondary return air box has a fan, a secondary return air inlet, a secondary return air duct, and an air supply outlet. The primary return air box is connected to the heat exchanger inlet, and the heat exchanger outlet is connected to the secondary return air box. The fan is installed in the secondary return air box and includes a volute, a fan wheel, and a motor. Its air intake is connected to the secondary return air box, and its air outlet is connected to the secondary return air box's air supply outlet. The secondary return air duct is installed in the secondary return air box. Its lower air intake is connected to the secondary return air inlet, and its upper air outlet is connected to the secondary return air box and connected to the secondary return air box shell. The upper air outlet is higher than the fan motor, and the fan motor is fitted inside it. All the air intake from the secondary return air inlet flows through the fan motor and then enters the secondary return air box.

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