Central air-conditioning system and control method thereof

Abstract

In a central air-conditioning system, regional flow balancing valves for controlling flow of water return branch pipes are arranged on the water return branch pipes, and energy balancing valves are arranged on water return pipes of tail-end fan coils respectively. A control method includes: detecting flow in the water return branch pipes, and adjusting the flow in the return branch pipes to be smaller than or equal to a branch pipe set flow value; and detecting the temperature of return water in the water return pipes of the tail-end fan coils, controlling the temperature of the return water in the water return pipes of the tail-end fan coils to be greater than or equal to a tail-end return water set temperature value, detecting the room temperature and adjusting the opening degree of the energy balancing valves in temperature controllers.

Claims

1. A central air-conditioning system, comprising: a refrigerating unit; a cooling water loop; a cooling water pump arranged on the cooling water loop; a cooling water pump frequency converter; a circulating water loop including a water inlet manifold and a water return manifold; a circulating water pump arranged on the circulating water loop; a circulating water pump frequency converter; a plurality of circulating water branches arranged in parallel on the circulating water loop, each of the plurality of circulating water branches including a water inlet branch pipe and a water return branch pipe; temperature controllers, fan coils, fresh air units and air handling units arranged in rooms, with the fan coils and the fresh air units being arranged in parallel on the same respective circulating water branches; a regional flow balancing valve for controlling the flow of each water return branch pipe arranged on each water return branch pipe; energy balancing valves, each arranged on a water return pipe of each fan coil and receiving signals output by respective ones of the temperature controllers; and a plurality of tail-end return water temperature sensors including a respective tail-end return water temperature sensor arranged on the respective water return pipe of each fan coil.

2. The central air-conditioning system of claim 1, wherein other energy balancing valves are respectively arranged on the water return pipes of the fresh air units and the air handling units and respectively receive signals output by the temperature controllers and tail-end return water temperature sensors that are arranged on the respective water return pipes of the fresh air units and the air handling units.

3. The central air-conditioning system of claim 1, wherein branch pipe return water temperature sensors are arranged on the water return branch pipes, and the regional flow balancing valves receive signals output by the branch pipe return water temperature sensors.

4. The central air-conditioning system of claim 1, wherein tail-end flow balancing valves for controlling return water flow are arranged on the water return pipes of the fresh air units and the air handling units and respectively receive signals output by the temperature controllers and tail-end return water temperature sensors that are arranged on the respective water return pipes of the fresh air units and the air handling units.

5. The central air-conditioning system of claim 2, wherein branch pipe return water temperature sensors are arranged on the water return branch pipes, and the regional flow balancing valves receive signals output by the branch pipe return water temperature sensors.

6. A control method for a central air-conditioning system including a refrigerating unit, a cooling water loop, a cooling water pump arranged on the cooling water loop, a cooling water pump frequency converter, a circulating water loop having a water inlet manifold and a water return manifold, a circulating water pump arranged on the circulating water loop, a circulating water pump frequency converter, a plurality of circulating water branches arranged in parallel on the circulating water loop, each of the plurality of circulating water branches including a water inlet branch pipe and a water return branch pipe, temperature controllers, fan coils, fresh air units and air handling units arranged in rooms, the fan coils and the fresh air units being arranged in parallel on the same respective circulating water branches, a regional flow balancing valve for controlling the flow of each water return branch pipe arranged on each water return branch pipe, an energy balancing valve arranged on a water return pipe of each fan coil that respectively receives signals output by respective ones of the temperature controllers, and a plurality of tail-end return water temperature sensors including a respective tail-end return water temperature sensor arranged on the respective water return pipe of each fan coil, said control method comprising the steps, performed simultaneously or sequentially, of: (a) detecting the flow in each water return branch pipe, and adjusting the opening degree of each regional flow balancing valve according to a branch pipe set flow value, so that the flow in the water return branch pipe is smaller than or equal to the branch pipe set flow value; and (b) detecting return water temperature in a water return pipe of each fan coil, adjusting the opening degree of each energy balancing valve according to a tail-end return water set temperature value, detecting the room temperature when the return water temperature in the water return pipe of each fan coil is greater than or equal to the tail-end return water set temperature value, and adjusting, by each temperature controller, the opening degree of each energy adjusting valve.

7. The control method for the central air-conditioning system of claim 6, wherein step (b) further comprises step (b1) detecting return water temperature in the water return pipe of each of the fresh air units and the air handling units, adjusting the opening degree of each energy balancing valve according to the tail-end return water set temperature value, detecting the room temperature when the return water temperature in the water return pipe of each of the fresh air units and the air handling units is greater than or equal to the tail-end return water set temperature value, and adjusting, by each temperature controller, the opening degree of each energy adjusting valve.

8. The control method for the central air-conditioning system of claim 6, wherein step (a) comprises detecting the flow in each water return branch pipe, adjusting the opening degree of each regional flow balancing valve according to the branch pipe set flow value, detecting the return water temperature in each water return branch pipe when the flow in the water return branch pipe is smaller than or equal to the branch pipe set flow value, and adjusting the opening degree of each regional flow balancing valve according to the branch pipe return water set temperature value.

9. The control method for the central air-conditioning system of claim 6, wherein step (b) further comprises simultaneously running step (b2) detecting return water flow in the water return pipe of each of the fresh air units and the air handling units, adjusting the opening degree of each tail-end flow balancing valve according to a tail-end set flow value, detecting return water temperature in the water return pipe of each of the fresh air units and the air handling units when the flow in the water return pipe of each of the fresh air units and the air handling units is smaller than or equal to the tail-end set flow value, adjusting the opening degree of each tail-end flow balancing valve according to the return water set temperature value, detecting the room temperature when the return water temperature in the water return pipe of each of the fresh air units and the air handling units is greater than or equal to the tail-end return water set temperature value, and adjusting, by each temperature controller, the opening degree of each tail-end flow balancing valve.

10. The control method for the central air-conditioning system of claim 7, wherein step (a) comprises detecting the flow in each water return branch pipe, adjusting the opening degree of each regional flow balancing valve according to the branch pipe set flow value, detecting the return water temperature in each water return branch pipe when the flow in the water return branch pipe is smaller than or equal to the branch pipe set flow value, and adjusting the opening degree of each regional flow balancing valve according to the branch pipe return water set temperature value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structural schematic diagram of embodiment 1 of the present invention;

(2) FIG. 2 is a control principle diagram of energy balancing valves in embodiment 1 of the present invention;

(3) FIG. 3 is a structural schematic diagram of embodiment 2 of the present invention;

(4) FIG. 4 is a control principle diagram of regional flow balancing valves in embodiment 2 of the present invention;

(5) FIG. 5 is a structural schematic diagram of embodiment 3 of the present invention;

(6) FIG. 6 is a control principle diagram of a tail-end flow balancing valve in embodiment 3 of the present invention;

(7) 1, refrigerating unit; 2, evaporator; 3, condenser; 4, circulating water pump; 5, cooling water pump; 6, circulating water return temperature sensor; 7, circulating water inlet temperature sensor; 8, cooling water inlet temperature sensor; 9, cooling water return temperature sensor; 10, regional flow balancing valve; 11, water collector; 12, water distributor; 13, air handling unit; 14, room; 15, energy balancing valve; 16, tail-end fan coil; 17, fresh air unit; 18, cooling water pump frequency converter; 19, circulating water pump frequency converter; 20, cooling tower; 21, differential pressure sensor; 22, by-pass valve; 23, temperature controller; 24, shunt protection device; 25, water inlet manifold; 26, water return manifold; 27, water inlet branch pipe; 28, water return branch pipe; 29, tail-end return water temperature sensor; 30, branch pipe return water temperature sensor; 31, tail-end flow balancing valve.

DETAILED DESCRIPTION OF THE INVENTION

(8) Since a central air-conditioning system is already very common, e.g. devices such as a fan coil, an air handling unit, a refrigerating unit and a water pump are all common devices in the prior art, the contents of the present invention will not be further described in detail.

Embodiment 1

(9) Refer to FIG. 1. A central air-conditioning system comprises a refrigerating unit 1, a cooling water loop, a cooling water pump 5 arranged on the cooling water loop, a cooling water pump frequency converter 18, a circulating water loop, a circulating water pump 4 arranged on the circulating water loop, a circulating water pump frequency converter 19, a plurality of circulating water branches arranged in parallel on the circulating water loop as well as temperature controllers 23, tail-end fan coils 16, fresh air units 17 and air handling units 13 arranged in rooms 14, the circulating water loop includes a water inlet manifold 25 and a water return manifold 26, and each circulating water branch includes a water inlet branch pipe 27 and a water return branch pipe 28; the tail-end fan coils 16, the fresh air units 17 and the air handling units 13 are arranged in parallel on the circulating water branches respectively; a regional flow balancing valve 10 for controlling the flow of each water return branch pipe is arranged on each water return branch pipe 28, and an energy balancing valve 15 is arranged on a water return pipe of each tail-end fan coil 16 and respectively receives signals output by the temperature controller 23 and a tail-end return water temperature sensor 29 which is arranged on the water return pipe of the tail-end fan coil 16. When the central air-conditioning system is applied to a refrigerating condition, different regions are divided according to the characteristics of buildings, e.g. according to different buildings or different floors of the same building, the regional flow balancing valve 10 is arranged on each regional water return branch pipe, and the flow of each water return branch pipe is detected through a flow sensor therein and compared with a set flow value to adjust the opening degree of the valve, so that the flow of each branch pipe is limited within a design value.

(10) An energy balancing valve 15 is arranged on a water return pipe of each of the tail-end fan coil 16, the air handling unit 13 and the fresh air unit 17 in each regional room 14, a tail-end return water temperature sensor 29 is arranged on the water return pipe of each tail-end device, and the opening degree of each energy balancing valve 15 is adjusted by comparing the return water temperature detected by the tail-end return water temperature sensor 29 with the set value, so that ensure that the return water temperature of the water return pipe of each tail-end device is greater than or equal to the set value, it is ensured that the heat exchange supply of the tail-end fan coils 16, the air handling units 13 and the fresh air units 17 is consistent with the load demand, the efficiency is the highest at the moment, and then the opening degree of the valve is finely adjusted according to the instruction given by the room temperature controller 23, so that the tail-end flow meets the requirement of comfortableness.

(11) Refer to FIG. 2, which is an adjusting principle diagram of each energy balancing valve 15, including the following steps:

(12) A1, detecting a tail-end return water temperature, acquiring the actual water temperature through the tail-end return water temperature sensor, and entering next step;

(13) A2, judging the cold/heat working condition, and entering next step;

(14) A3, selecting a return water temperature set value according to the cold/heat working condition, and entering next step;

(15) A4, comparing the actual water temperature with the return water temperature set value, and entering next step;

(16) A5, judging whether the actual water temperature is smaller than or equal to the set value, if so, entering step A6, otherwise, entering step A7;

(17) A6, outputting an instruction to reduce the opening degree of the valve, and returning to step A1;

(18) A7, receiving the signal control of the room temperature controller, resetting the return water temperature set value as a temperature controller set value, and entering next step;

(19) A8, judging whether the actual water temperature is greater than the set value, if so, entering step A9, otherwise, entering step A10;

(20) A9, outputting an instruction to increase the opening degree of the valve, and returning to step A1; and

(21) A10, outputting an instruction to reduce the opening degree of the valve, and returning to step A1.

(22) The refrigerating unit 1 arranged on the circulating water loop mainly includes an evaporator 2 and a condenser 3. A cooling water inlet temperature sensor 8 inserted onto a water inlet pipeline of the condenser 3 and a cooling water return temperature sensor 9 inserted onto a water outlet pipeline of the condenser 3 send detected water temperature signals to the cooling water pump frequency converter 18, and the cooling water pump 5 positioned on the circulating water loop and connected with the condenser 3 is controlled by the output of the cooling water pump frequency converter 18, so that the working efficiency of the cooling water pump 5 is controlled. Similarly, a circulating water return temperature sensor 6 inserted onto a water inlet pipeline of the evaporator 2 and a circulating water inlet temperature sensor 7 inserted onto a water outlet pipeline of the evaporator 2 send detected water temperature signals to the circulating water pump frequency converter 19, and the circulating water pump 4 positioned on the circulating water loop and connected with the evaporator 2 is controlled by the output of the circulating water pump frequency converter 19, so that the working efficiency of the circulating water pump 4 is controlled. A cooling tower 20 connected to the cooling water loop cools water after heat exchange of the condenser. A differential pressure sensor 21 is connected between the water collector 11 and the water distributor 12 which are connected to the circulating water loop, the shunt protection device 24 receives signals of the differential pressure sensor 21 and the temperature sensor 7, and a by-pass valve 22 arranged between the water supply and return loops is controlled by the output of the shunt protection device, so that safe use of a main unit and normal operation of pipelines are ensured.

Embodiment 2

(23) Refer to FIG. 3. A central air-conditioning system comprises a refrigerating unit 1, a cooling water loop, a cooling water pump 5 arranged on the cooling water loop, a cooling water pump frequency converter 18, a circulating water loop, a circulating water pump 4 arranged on the circulating water loop, a circulating water pump frequency converter 19, a plurality of circulating water branches arranged in parallel on the circulating water loop, as well as temperature controllers 23, tail-end fan coils 16, fresh air units 17 and air handling units 13 arranged in rooms 14, wherein the circulating water loop includes a water inlet manifold 25 and a water return manifold 26, and each circulating water branch includes a water inlet branch pipe 27 and a water return branch pipe 28; the tail-end fan coils 16, the fresh air units 17 and the air handling units 13 are arranged in parallel on the circulating water branches respectively; a regional flow balancing valve 10 for controlling the flow of each water return branch pipe is arranged on each water return branch pipe 28, and an energy balancing valve 15 is arranged on a water return pipe of each tail-end fan coil 16 and respectively receives signals output by the temperature controller 23 and a tail-end return water temperature sensor 29 which is arranged on the water return pipe of the tail-end fan coil 16. A branch pipe return water temperature sensor 30 is arranged on each water return branch pipe 28, and the regional flow balancing valves 10 receive signals output by the branch pipe return water temperature sensors 30.

(24) When the central air-conditioning system is applied to a refrigerating condition, different regions are divided according to the characteristics of buildings, e.g. according to different buildings or different floors of the same building, the regional flow balancing valve 10 is arranged on each regional water return branch pipe, and the flow of each water return branch pipe is detected through a flow sensor therein and compared with a set flow value to adjust the opening degree of the valve, so that the flow of each branch pipe is limited within a design value.

(25) Refer to FIG. 4, which is a control principle diagram of each regional flow balancing valve, including the following steps:

(26) B1, detecting a return water temperature in each water return branch pipe, acquiring the actual water temperature through each branch pipe return water temperature sensor, and entering next step;

(27) B2, judging whether the setting of the cold/heat working condition is changed, if so, entering step B3, otherwise, entering step B4;

(28) B3, selecting a return water temperature set value according to the current cold/heat working condition, and entering step B7;

(29) B4, detecting the actual return water flow value, and entering next step;

(30) B5, comparing whether the actual return water flow value is smaller than or equal to a set value, if so, entering step B7, otherwise, entering step B6;

(31) B6, outputting an instruction to reduce the opening degree of the valve, and returning to step B4;

(32) B7, comparing whether the actual water temperature is greater than or equal to the return water temperature set value, if not, entering step B6, otherwise, entering step B8; and

(33) B8, outputting an instruction to increase the opening degree of the valve, and returning to step B1.

(34) An energy balancing valve 15 is arranged on a water return pipe of each of the tail-end fan coil 16, the air handling unit 13 and the fresh air unit 17 in each regional room 14, a tail-end return water temperature sensor 29 is arranged on the water return pipe of each tail-end device, and the opening degree of each energy balancing valve 15 is adjusted by comparing the return water temperature detected by the tail-end return water temperature sensor 29 with the set value, so that the return water temperature of the water return pipe of each tail-end device is greater than or equal to the set value, it is ensured that the heat exchange supply of the tail-end fan coils 16, the air handling units 13 and the fresh air units 17 is consistent with the load demand, the efficiency is the highest at the moment, and then the opening degree of the valve is finely adjusted according to the instruction given by the room temperature controller 23, so that the tail-end flow meets the requirement of comfortableness.

(35) The adjusting principle of each energy balancing valve 15 is the same as that in embodiment 1, and is not repeatedly described herein.

(36) The refrigerating unit 1 arranged on the circulating water loop mainly includes an evaporator 2 and a condenser 3. A cooling water inlet temperature sensor 8 inserted onto a water inlet pipeline of the condenser 3 and a cooling water return temperature sensor 9 inserted onto a water outlet pipeline of the condenser 3 send detected water temperature signals to the cooling water pump frequency converter 18, and the cooling water pump 5 positioned on the circulating water loop and connected with the condenser 3 is controlled by the output of the cooling water pump frequency converter 18, so that the working efficiency of the cooling water pump 5 is controlled. Similarly, a circulating water return temperature sensor 6 inserted onto a water inlet pipeline of the evaporator 2 and a circulating water inlet temperature sensor 7 inserted onto a water outlet pipeline of the evaporator 2 send detected water temperature signals to the circulating water pump frequency converter 19, and the circulating water pump 4 positioned on the circulating water loop and connected with the evaporator 2 is controlled by the output of the circulating water pump frequency converter 19, so that the working efficiency of the circulating water pump 4 is controlled. A cooling tower 20 connected to the cooling water loop cools water after heat exchange of the condenser. A differential pressure sensor 21 is connected between the water collector 11 and the water distributor 12 which are connected to the circulating water loop, the shunt protection device 24 receives signals of the differential pressure sensor 21 and the temperature sensor 7, and a by-pass valve 22 arranged between the water supply and return loops is controlled by the output of the shunt protection device 24, so that safe use of a main unit and normal operation of pipelines are ensured.

Embodiment 3

(37) Refer to FIG. 5, which shows another central air-conditioning system, comprising a refrigerating unit 1, a cooling water loop, a cooling water pump 5 arranged on the cooling water loop, a cooling water pump frequency converter 18, a circulating water loop, a circulating water pump 4 arranged on the circulating water loop, a circulating water pump frequency converter 19, a plurality of circulating water branches arranged in parallel on the circulating water loop, as well as temperature controllers 23, tail-end fan coils 16, fresh air units 17 and air handling units 13 arranged in rooms 14, wherein the circulating water loop includes a water inlet manifold 25 and a water return manifold 26, and each circulating water branch includes a water inlet branch pipe 27 and a water return branch pipe 28; the tail-end fan coils 16, the fresh air units 17 and the air handling units 13 are arranged in parallel on the circulating water branches respectively; a regional flow balancing valve 10 for controlling the flow of each water return branch pipe is arranged on each water return branch pipe 28, and an energy balancing valve 15 is arranged on a water return pipe of each tail-end fan coil 16 and respectively receives signals output by the temperature controller 23 and a tail-end return water temperature sensor 29 which is arranged on the water return pipe of the tail-end fan coil 16.

(38) When the central air-conditioning system is applied to a refrigerating condition, different regions are divided according to the characteristics of buildings, e.g. according to different buildings or different floors of the same building, the regional flow balancing valve 10 is arranged on each regional water return branch pipe, and the flow of each water return branch pipe is detected through a flow sensor therein and compared with a set flow value to adjust the opening degree of the valve, so that the flow of each branch pipe is limited within a design value.

(39) An energy balancing valve 15 is arranged on the water return pipe of each tail-end fan coil 16 in each regional room 14, a tail-end flow balancing valve 31 is arranged on the water return pipe of each of the air handling units 13 and the fresh air units 17, a tail-end return water temperature sensor 29 is arranged on the water return pipe of each tail-end device, and the opening degree of each energy balancing valve 15 is adjusted by comparing the return water temperature detected by the tail-end return water temperature sensor 29 with a set value, so that the return water temperature of the water return pipe of each tail-end device is greater than or equal to the set value, it is ensured that the heat exchange supply of the tail-end fan coils 16 is consistent with the load demand, the efficiency the is highest at the moment, and then the opening degree of the valve is finely adjusted according to the instruction given by the room temperature controller 23, so that the tail-end flow meets the requirement of comfortableness.

(40) Refer to FIG. 6, which is a control principle diagram of each tail-end flow balancing valve 31, including the following steps:

(41) C1, detecting a return water temperature in each water return pipe, acquiring the actual water temperature through each tail-end return water temperature sensor, and entering next step;

(42) C2, judging whether the setting of the cold/heat working condition is changed, if so, entering step C3, otherwise, entering step C4;

(43) C3, selecting a return water temperature set value according to the current cold/heat working condition, and entering step C7;

(44) C4, detecting the actual return water flow value, and entering next step;

(45) C5, comparing whether the actual return water flow value is smaller than or equal to a set value, if so, entering step C7, otherwise, entering step C6;

(46) C6, outputting an instruction to reduce the opening degree of the valve, and returning to step C4;

(47) C7, comparing whether the actual water temperature is smaller than or equal to the return water temperature set value, if not, entering step C6, otherwise, entering step C8;

(48) C8, receiving the signal control of the room temperature controller, resetting the return water temperature set value as a temperature controller set value, and entering next step;

(49) C9, judging whether the actual water temperature is greater than the set value, if so, entering step C10, otherwise, entering step C11;

(50) C10, outputting an instruction to increase the opening degree of the valve, and returning to step C1; and

(51) C11, outputting an instruction to reduce the opening degree of the valve, and returning to step C1.

(52) The refrigerating unit 1 arranged on the circulating water loop mainly includes an evaporator 2 and a condenser 3. A cooling water inlet temperature sensor 8 inserted onto a water inlet pipeline of the condenser 3 and a cooling water return temperature sensor 9 inserted onto a water outlet pipeline of the condenser 3 send detected water temperature signals to the cooling water pump frequency converter 18, and the cooling water pump 5 positioned on the circulating water loop and connected with the condenser 3 is controlled by the output of the cooling water pump frequency converter 18, so that the working efficiency of the cooling water pump 5 is controlled. Similarly, a circulating water return temperature sensor 6 inserted onto a water inlet pipeline of the evaporator 2 and a circulating water inlet temperature sensor 7 inserted onto a water outlet pipeline of the evaporator 2 send detected water temperature signals to the circulating water pump frequency converter 19, and the circulating water pump 4 positioned on the circulating water loop and connected with the evaporator 2 is controlled by the output of the circulating water pump frequency converter 19, so that the working efficiency of the circulating water pump 4 is controlled. A cooling tower 20 connected to the cooling water loop cools water after heat exchange of the condenser. A differential pressure sensor 21 is connected between the water collector 11 and the water distributor 12 which are connected to the circulating water loop, the shunt protection device 24 receives signals of the differential pressure sensor 21 and the temperature sensor 7, and a by-pass valve 22 arranged between the water supply and return loops is controlled by the output of the shunt protection device 24, so that safe use of a main unit and normal operation of pipelines are ensured.

(53) The beneficial effects of the present invention will be further described below through experiments.

(54) The test environment is a two-floor commercial office building which includes a hall, a meeting room, offices and a small warehouse. A central air-conditioning system is mainly used for meeting the requirement of refrigeration in summer, the cold supply area is 1740 m.sup.2, and the number of permanent persons is 151. The environment is divided into three regions, the hall and the meeting room are regarded as the first region, the offices are regarded as the second region, the warehouse is regarded as the third region, a circulating water branch pipe is arranged in each region, the tail-end fan coil in each room is connected in parallel to the circulating water branch pipe of each region. Three SPV020F80 type regional flow balancing valves produced by Guangzhou SINRO (Fogang) Air-Conditioning & Chiller Equipment Co., Ltd. are arranged on each regional water return branch pipe; 24 SEV01G20 type energy balancing valves produced by Guangzhou SINRO (Fogang) Air-Conditioning & Chiller Equipment Co., Ltd. are arranged on the water return pipeline of each tail-end device; the temperature controller in each room sets the temperature at 25° C., and the tail-end cold supply water temperature is set on the basis that the inlet water is 7° C. and the return water is 12° C.; a total flow meter for detecting the water quantity for cold supply is arranged on a circulating water manifold, the circulating water pump and the cooling water pump are GD65-30 type water pumps produced by GUANGYI PUMP, the electric energy meter is a DT862 type three-phase four-wire watt-hour meter produced by Shanghai Hayi, and the timer is a (Xinling) ZN4896 type multifunctional time relay produced by Xinling Electrical Co., Ltd.

(55) Operating data are selected below for description:

Experiment 1

(56) Environmental (dry and wet bulb) temperature: 30° C. and 26.9° C. recorded at 11 o'clock, 33.5° C. and 27° C. recorded at 16 o'clock,

(57) TABLE-US-00001 recording time 8:15 8:30 9:00 10:00 11:00 12:00 14:00 15:00 16:00 17:00 running 0.43 0.67 1.27 2.32 3.35 4.17 6.2 7.08 8.23 9.15 time (h) temperature return 32.4 20 14.5 12.9 12.5 11 11.3 12 12.3 10.5 difference water transmitting effluent 29 16.2 11 8.9 9.7 7.2 7.5 9 9.6 6.4 reading (° C.) frequency voltage E00 E00 10 10 10 8.2 7.6 10 10 8.4 converter frequency 50 42.9 48.8 50 50 40.5 39.7 50 50 41.6 reading current 8.1 8.3 8.3 7.8 7.5 4.2 3.7 7.7 8 5.3 torque 96.7 97.5 94.8 92 89.3 41.4 35 92.1 95.2 55.6 electric 1259 1260 1263 1268.3 1272.6 1275.3 1278.6 1280.8 1283.2 1284.6 energy meter reading (kWh) flow value 25.6 26.1 24.5 5 21.3 16.3 13.2 23.3 23.5 16.3 (m.sup.3)

(58) Each of the circulating water pump and the cooling water pump consumes 3.6 kWh per hour, runs 9 hours every day and consumes 32.4 kWh in a day under a power frequency, and consumes 2.94 kWh per hour, runs 9 hours every day and consumes 26.46 kWh in a day under a frequency conversion state after the method of the present invention is adopted, so that compared with those in the power frequency state, the electricity is saved by 5.94 kWh, and the energy is saved by 18.3%.

Experiment 2

(59) Environmental (dry and wet bulb) temperature: 27° C. and 21.5° C. recorded at 12 o'clock, 28.5° C. and 21.5° C. recorded at 15 o'clock, 27.9° C. and 20.6° C. recorded at 17 o'clock

(60) TABLE-US-00002 running time (h) 261.68 262.87 263.82 265.33 266.35 267.55 268.30 temperature return 11.7 11.2 10.8 10.2 11.1 10.6 11.2 difference water transmitting effluent 7.6 7.8 7.9 6.4 7.6 7.1 10.7 reading voltage 9.6 6.8 6.4 7.4 6.8 6.6 6 frequency frequency 48.6 34.4 32.3 37.4 34.3 33.3 30.3 converter current 6.9 4.8 4.5 4.3 4.5 4.3 3.7 reading torque 83.5 41.2 37 39.5 38.4 36.3 27.5 electric 2671.5 2673.8 2675.9 2678.1 2679.8 2681.8 2683.1 energy meter reading flow value 22.7 11.7 12.6 9.9 10.3 12.1 8.06

(61) Each of the circulating water pump and the cooling water pump consumes 3.6 kWh per hour, runs 8 hours every day and consumes 28.8 kWh in a day under a power frequency, and consumes 1.75 kWh per hour, runs 8 hours every day and consumes 14 kWh in a day under a frequency conversion state after the method of the present invention is adopted, so that compared with the power frequency state, the electricity is saved by 14.8 kWh every day, and the energy is saved by 51.4%.

(62) The above detailed description is specific description of the feasible embodiments of the present invention, the embodiments are not used for limiting the patent range of the present invention, and all equivalent implementations or alterations made without departing from the present invention should be included within the patent range of the present.