A frequency converter room air conditioning and ventilation coupling cooling system and a use method thereof

Abstract

The application provides a variable frequency converter room air conditioner and ventilation coupling cooling system and a use method, which comprises a sand removing device, an air conditioning unit, a variable frequency converter room, a variable frequency fan box, outdoor fresh air is connected with the first sand removing device and the second sand removing device through pipelines respectively, the first sand removing device is connected with the air conditioning unit through a pipeline, the second sand removing device is connected with the variable frequency fan box through a pipeline, the air conditioning unit and the variable frequency fan box are connected with the variable frequency converter room through pipelines, the variable frequency converter room is connected with a first exhaust assembly and a second exhaust assembly, the first exhaust assembly is communicated with the outside, and the second exhaust assembly is connected with the variable frequency fan box. The application has the beneficial effects that a good indoor temperature and humidity and cleanliness environment is provided for the variable frequency converter, the demand of pipelines on indoor space is reduced, and good energy saving performance is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of frequency converter room cooling, and particularly relates to a frequency converter room air conditioner and ventilation coupled cooling system and a use method. BACKGROUND

[0002] The heat dissipation of the equipment in the frequency converter room is generally very large, and about 2% to 4% of the power consumption of the frequency converter will become heat during normal operation. For example, the heat dissipation of a 1000kW frequency converter is about 40kW. These heat needs to be timely discharged to the outdoor to prevent the frequency converter from overheating and further affect the normal operation of the process production equipment.

[0003] The normal working environment of the frequency converter can refer to the national standards (GBT 12668.4-2006, Part 4 of the Speed Regulation Electrical Drive System: General Requirements for AC Voltage 1000V and Above but Not More Than 35kV AC Speed Regulation Electrical Drive System Rated Value; GB / T 12668.2-2002, Part 2 of the Speed Regulation Electrical Drive System: General Requirements for Low Voltage AC Variable Frequency Electrical Drive System Rated Value), and the related parameters are as follows: temperature 5-40℃, relative humidity 5-85%, and no condensation. In actual design, in order to be safe, the room temperature is usually designed to be 5-35℃, and the relative humidity is 5-85%. According to the meteorological conditions of the project location, indoor environmental requirements, equipment heat dissipation and other factors, and combined with the specific requirements of the project, the unit air conditioner cooling or direct current exhaust cooling mode is usually selected.

[0004] The unit air conditioner cooling mode can better meet the indoor temperature requirements in winter and summer, and has the advantages of simple system, small pipeline, small occupation, not affected by outdoor sand and the like. However, the indoor residual heat is all borne by the air conditioner, the power consumption is large, the air conditioner needs to be operated in winter, and the requirement for the equipment is high.

[0005] Compared with the air conditioner cooling, the direct current exhaust cooling mode has great energy saving potential. However, due to the large exhaust capacity, the equipment and the air pipe have high space requirements, which will bring difficulties in the arrangement of the exhaust pipe and the fan and the setting of the air baffle. In addition, the air baffle has poor air cleaning effect, and once the filter screen of the air baffle was blocked due to the dirty air in the factory area, the frequency converter overheating alarm fault occurred. Furthermore, the frequency converter is powered by the factory air exhaust fan arranged at the top, the air in the working area is introduced through the lower air baffle, and then the air is discharged to the upper part of the room through the outlet of the exhaust fan. Therefore, the indoor temperature of the frequency converter room is high at the upper part and low at the lower part. However, in actual engineering, the direct current exhaust cooling mode generally takes the average indoor temperature as the control target, and few engineering examples directly use the indoor temperature distribution. SUMMARY

[0006] Therefore, the application aims to provide a frequency converter room air conditioner and ventilation coupling cooling system and a use method to solve the problems of the unit air conditioner cooling and the direct current air exhaust cooling.

[0007] To achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0008] A use method of a frequency converter room air conditioner and ventilation coupling cooling system, comprising the following steps:

[0009] S1: calculating the frequency converter body air outlet temperature tp according to the design temperature of the frequency converter room, calculating the outdoor air conditioner design dew point temperature tl, judging the frequency converter body air outlet temperature and the design meteorological parameter, if the frequency converter body air outlet temperature is greater than or equal to the design meteorological parameter, then performing S2, otherwise using the air conditioner;

[0010] S2: calculating the total heat Q2 of the frequency converter and the total ventilation volume G2 of the frequency converter fan;

[0011] S3: calculating the percentage k1 of the system design ventilation volume G1 and the total exhaust volume G2 of the frequency converter body, calculating the summer air supply temperature ts1 of the air supply system, if ts1≥tl, then performing S4, otherwise adjusting k1 and performing step S3;

[0012] S4: calculating the equipment rated cooling capacity Q3 and the equipment rated air volume G5;

[0013] S5: calculating the winter system minimum ventilation volume G4, and calculating the ratio k2 of the winter system minimum ventilation volume G4 of the frequency fan and the equipment rated air volume G5;

[0014] S6: if k2≥the lower limit kmin of the ratio of the minimum and maximum air volume of the frequency fan, calculating the winter air supply temperature ts3, otherwise adjusting G4 and performing S5,

[0015] S7: if ts3<the minimum value tsmin of the winter air supply system air supply temperature, adjusting G4 and performing S5, if ts3≥the winter outdoor air conditioner related dry bulb temperature tw3, calculating the maximum bypass air volume output result, otherwise directly outputting the design ventilation volume G1, the equipment rated air volume G5, the equipment rated cooling capacity Q3 and the system minimum ventilation volume G4s.

[0016] The calculation formula of the body air outlet temperature tp in the step S1 is:

[0017] Q=0.28c p ρ wn G(t out -t in )

[0018] Q: the indoor heat load, approximately equal to the total heat dissipation W of the frequency converter;

[0019] cp: specific heat capacity of air at constant pressure, cp = 1 kJ / (kg °C);

[0020] p wn : air density at the inlet air calculation temperature, approximately 1.2 kg / m 3 ;

[0021] G: ventilation quantity (m 3 / h);

[0022] t in : inlet air temperature (°C)

[0023] t out : outlet air temperature (°C)

[0024] The body outlet air temperature tp is calculated according to the formula.

[0025] The outdoor air conditioning dew point temperature tl in step S1 is obtained according to the psychrometric chart.

[0026] The calculation method of the total heat Q2 of the frequency converter in step S2 is as follows:

[0027] The total heat Q2 of the frequency converter = heat of a single frequency converter x number of frequency converters;

[0028] The calculation method of the total ventilation quantity G2 of the frequency converter fan is as follows:

[0029] The total ventilation quantity G2 of the frequency converter fan = ventilation quantity of a single frequency converter fan x number of fans.

[0030] After step S3, the single air conditioning supply air temperature ts2 is calculated, and when ts2≤tl, the frequency conversion air conditioning unit also has a cooling section at this time, and the frequency conversion fan box starts to cool at this time. At this time, the frequency conversion fan box and the air conditioning unit jointly cool, which can reduce the cooling capacity of the air conditioning unit, avoid the generation of condensate water due to the too low supply air temperature of the air conditioning unit, and save resources. Otherwise, only the frequency conversion air conditioning unit has a cooling section.

[0031] Further, the calculation method of the maximum bypass air quantity G3 in step S7 is as follows:

[0032] G3 = G4 * (ts3-tw3) / (tp-tw3)

[0033] G3 is the maximum bypass air quantity;

[0034] G4 is the minimum ventilation quantity of the system;

[0035] ts3 is the supply air temperature of the winter air supplement system;

[0036] tw3 is the winter air conditioning outdoor calculation dry bulb temperature;

[0037] tp is the high temperature zone temperature (approximately take the frequency converter body out of the wind temperature);

[0038] A frequency converter room air conditioner and ventilation coupling cooling system, comprising a sand removal device, an air conditioning unit, a frequency converter room, a frequency converter fan box,

[0039] The outdoor fresh air is connected with the first sand removal device and the second sand removal device through the pipeline respectively, the first sand removal device is connected with the air conditioning unit through the pipeline,

[0040] The second sand removal device is connected with the frequency converter fan box through the pipeline, the air conditioning unit and the frequency converter fan box are connected with the frequency converter room through the pipeline, the frequency converter room is connected with the first exhaust assembly and the second exhaust assembly, the first exhaust assembly is connected with the outdoor, and the second exhaust assembly is connected with the frequency converter fan box.

[0041] Further, the air conditioning unit is connected with the outdoor fresh air through the first pipeline, the first sand removal device is arranged on the first pipeline, the first pipeline is provided with a first valve, and the first valve is arranged between the first sand removal device and the air conditioning unit;

[0042] The air conditioning unit is connected with the frequency converter room through the second pipeline, and the second pipeline is provided with a second valve;

[0043] The frequency converter fan box is connected with the outdoor fresh air through the third pipeline, the second sand removal device is arranged on the third pipeline, the third pipeline is provided with a third valve, and the third valve is arranged between the second sand removal device and the frequency converter fan box.

[0044] The frequency converter fan box is connected with the frequency converter room through the fourth pipeline, and the fourth pipeline is provided with a fourth valve.

[0045] Further, the frequency converter room is connected with the first exhaust assembly through the fifth pipeline, the fifth pipeline is provided with a fifth valve, the fifth exhaust assembly comprises a fan, the fan is arranged on the fifth pipeline, and the fifth pipeline exhausts to the outdoor.

[0046] The frequency converter room is connected with the second exhaust assembly through the sixth pipeline, the sixth pipeline is provided with a sixth valve, the second exhaust assembly comprises a frequency converter fan, and the frequency converter fan is arranged on the sixth pipeline;

[0047] The sixth pipeline is connected with the frequency converter fan box through the bypass pipeline, the sixth pipeline is connected with the outside, and the sixth pipeline exhausts to the outdoor.

[0048] Further, the bypass pipeline is provided with a seventh valve.

[0049] Further, the air conditioning unit is composed of a first fresh air section, a first primary filter section, a first medium-efficiency filter section, a surface cooling section and a fan section, and the frequency converter fan box is composed of a second fresh air section, a second primary filter section, a second medium-efficiency filter section and a frequency converter fan section.

[0050] The frequency converter chamber comprises several frequency converters, the top of the frequency converter is provided with an exhaust fan, the second pipeline and the fourth pipeline are connected with the first converging pipeline through a tee joint;

[0051] The first converging pipeline is provided with several air supply openings, the air supply openings are arranged in the frequency converter chamber to send outdoor air to the lower part of the frequency converter.

[0052] The fifth pipeline and the sixth pipeline are connected with the second converging pipeline through a tee joint, the second converging pipeline is provided with several exhaust openings, and the exhaust openings are arranged above the frequency converter chamber.

[0053] Compared with the prior art, the frequency converter chamber air conditioner and ventilation coupling cooling system and the use method have the following advantages:

[0054] The system fully combines the distribution characteristics of the upper and lower layers of the temperature in the frequency converter chamber, the high-temperature area exhausts air, and the working area supplies air, the exhaust air temperature is tp, and the indoor control target is tn, through the air conditioner ventilation coupling cooling technology, the indoor temperature demand can be met, the G1 system design ventilation volume is smaller than the total ventilation volume of the G2 frequency converter, a good indoor temperature and humidity and cleanliness environment is provided for the frequency converter, the demand of the pipeline on the indoor space is reduced, and good energy-saving performance is achieved. DETAILED DESCRIPTION

[0055] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application is not limited by the improper interpretation of the accompanying drawings. In the drawings:

[0056] Figure 1 A frequency converter chamber air conditioner and ventilation coupling cooling system according to an embodiment of the present application;

[0057] Figure 2 A frequency converter chamber air conditioner and ventilation coupling cooling system according to an embodiment of the present application;

[0058] Figure 3 A high-voltage frequency converter chamber according to an embodiment of the present application;

[0059] Figure 4 An enthalpy humidity chart according to an embodiment of the present application.

[0060] Explanation of reference signs:

[0061] 1, the first fresh air section; 2, the first primary filter section; 3, the first medium efficiency filter section; 4, the surface cooling section; 5, the fan section; 6, the second fresh air section; 7, the second primary filter section; 8, the second medium efficiency filter section; 9, the variable frequency fan section; 10, the air supply outlet; 11, the exhaust outlet; 12, the first sand removal device; 13, the second sand removal device; 14, the air conditioning unit; 15, the variable frequency fan box; 16, the first valve; 17, the second valve; 18, the third valve; 19, the fourth valve; 20, the fifth valve; 21, the fan; 22, the sixth valve; 23, the variable frequency fan; 24, the frequency converter; 25, the exhaust fan; 26, the seventh valve. DETAILED DESCRIPTION

[0062] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0063] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the term "a plurality of" means two or more.

[0064] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0065] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0066] Considering the temperature distribution characteristics in the frequency converter room, it can be roughly identified that there is a hypothetical boundary, with the frequency converter air outlet as the boundary, the upper part is a high temperature area with higher temperature, corresponding to the frequency converter air outlet temperature tp; the lower part is a lower temperature working area, which is the temperature tn that the frequency converter really wants to control.

[0067] The system is composed of the following parts: sand removal louvers, air conditioning unit 14, variable frequency fan box 15, fan 21, variable frequency fan 23, multiple air supply outlets 10, multiple exhaust outlets 11, and necessary pipeline valves. Among them, the air conditioning unit 14 is composed of the first fresh air section 1, the first primary filter section 2, the first medium-efficiency filter section 3, the cooling section 4, and the first fan section 5; the variable frequency fan box 15 is composed of the second fresh air section 6, the second primary filter section 7, the second medium-efficiency filter section 8, and the variable frequency fan section 9. The variable frequency converter room generally has multiple variable frequency converters, and each variable frequency converter is equipped with an air inlet louver and an exhaust fan. tp is the high-temperature zone temperature, which is approximately the variable frequency converter outlet air temperature; tn is the working zone temperature; tw is the outdoor air temperature; ts is the supply air temperature. G1 is the system design ventilation rate; G2 is the total ventilation rate of the variable frequency converter; and G3 is the system design bypass ventilation rate.

[0068] The only difference between the air conditioning unit 14 and the variable frequency fan box 15 is the cooling section 4. According to specific projects, the variable frequency fan box 15 can also have a cooling section, i.e., the form of the air conditioning unit 14 is used to improve the support capacity of the refrigeration system.

[0069] The outdoor air first passes through the sand removal louvers for primary filtration to reduce the working load on the filters inside the air conditioning unit 14 and the variable frequency fan box 15.

[0070] The air after primary filtration by the sand removal louvers is divided into two paths: one path enters the air conditioning unit 14, is further filtered by the first fresh air section 1, the first primary filter section 2, and the first medium-efficiency filter section 3 to form clean air, and then is cooled by the cooling section 4 and pressurized by the fan 5 section; the other path enters the variable frequency fan box 15, is further filtered by the second fresh air section 6, the second primary filter section 7, and the second medium-efficiency filter section 8 to form clean air, and then is pressurized by the variable frequency fan section 9; the air after processing by the air conditioning unit 14 and the variable frequency fan box 15 is sent to the indoor working zone through the air duct and the air supply outlet 10, with a ventilation rate of G1 and a temperature of ts.

[0071] The mixed air after mixing with the return air from the high-temperature zone forms the working zone air, with a temperature of tn. Under the action of the exhaust fan 25 of the variable frequency converter 24, the mixed air enters the variable frequency converter 24 cabinet through the air inlet louver, is heat-exchanged, and is then discharged to the high-temperature zone through the exhaust fan 25, with a temperature of tp. Part of the air entering the high-temperature zone is discharged to the outdoor air through the air duct and the exhaust outlet 11 under the action of the fan 21 and the variable frequency fan 23; the other part of the air serves as the return air and mixes with the supply air.

[0072] When the outdoor temperature is higher than the supply air temperature ts1, the air conditioning unit 14 and the variable frequency fan box 15 work simultaneously, the surface cooling section 4 of the air conditioning unit 14 is opened, and the temperature tn of the indoor working area is maintained; the refrigerating capacity only supplements the cold load caused by the temperature difference between the outdoor air temperature tw and the supply air temperature ts1. The air conditioning unit 14, the variable frequency fan box 15, the fan 21 and the variable frequency fan 23 all work according to the full load design air volume.

[0073] When the outdoor temperature is lower than the supply air temperature ts1, the air conditioning unit 14, the variable frequency fan box 15, the fan 21 and the variable frequency fan 23 all work simultaneously, but the surface cooling section 4 stops refrigeration, the variable frequency fan box 15 and the variable frequency fan 23 gradually reduce the system ventilation volume through frequency conversion adjustment, and the temperature tn of the indoor working area is maintained; as the outdoor temperature further decreases, the air conditioning unit 14 and the fan 21 will stop working, only the variable frequency fan box 15 and the variable frequency fan 23 work simultaneously, and frequency conversion adjustment is performed; in winter, in order to prevent the indoor temperature from being too low, the variable frequency fan 23 will mix part of the exhaust air with outdoor fresh air through the bypass air pipe, and then send the mixed air into the indoor working area through the variable frequency fan box 15, so as to maintain the temperature tn of the indoor working area, and the size of the bypass air volume is adjusted by the opening degree of the seventh valve 26 (electric valve).

[0074] The first valve 16 and the second valve 17 are opened and closed simultaneously with the air conditioning unit 14, the third valve 18 and the fourth valve 19 are opened and closed simultaneously with the variable frequency fan box 15, the fifth valve 20 is opened and closed simultaneously with the fan 21, and the sixth valve 22 is opened and closed simultaneously with the variable frequency fan 23.

[0075] For the system, there is a certain standby relationship between the air conditioning unit 14 and the variable frequency fan box 15, and there is also a certain standby relationship between the fan 21 and the variable frequency fan 23. Once one of the devices fails, the other device can still meet 50% of the air supply or exhaust volume, and the insufficient or excessive air volume can be temporarily supplemented or removed by the door and window infiltration, so the reliability of the system is high.

[0076] The system fully combines the distribution characteristics of the indoor temperature of the frequency converter, the exhaust air of the high temperature area and the supply air of the working area, takes tp as the exhaust air temperature and tn as the indoor control target, and through the air conditioning ventilation coupling cooling technology, the G1 system design ventilation volume is smaller than the total ventilation volume of the G2 frequency converter body while meeting the indoor temperature demand, the frequency converter is provided with a good indoor temperature and humidity and cleanliness environment, the demand of the pipeline on the indoor space is reduced, and good energy saving performance is achieved.

[0077] A coal chemical project in a city in the northwest has a high-voltage frequency converter room (27m long, 16m wide and 5.6m high, see the attached Figure 3 ), which is arranged with 8 sets of frequency converters, and the heat dissipation of a single unit is 31kW. The fan matched with a single frequency converter is 15600m 3 / h, while running, the total heat dissipation is 248kW, the total ventilation of the frequency converter body G2 is 124800m 3 / h. Weather conditions: the outdoor air dry bulb calculation temperature tw in summer is 32.2℃, and the outdoor air dry bulb calculation temperature tw in winter is -19.3℃. Indoor design requirements: design temperature 5-35℃, relative humidity 5-85%, and no condensation. The design is made according to the application.

[0078] Firstly, the temperature tn of the lower working area is 35℃, and the temperature tp of the upper high-temperature area is 40.9℃, which can be obtained by taking the frequency converter outlet temperature as the boundary.

[0079] Considering the weather conditions of the project site, indoor environmental requirements, equipment heat dissipation and technical and economic feasibility of the project, the system design ventilation G1 is 62400m 3 / h, which is half of the total ventilation G2 of the frequency converter body, and the supply air temperature ts is 28.0℃ under the summer design condition.

[0080] The outdoor air first passes through the sand removal louvers for primary filtration, and some sand, gravel, paper scraps, leaves and other large particulate matters are effectively removed, which can reduce the working load of the filters inside the air conditioning unit 14 and the frequency converter fan box 15.

[0081] The air after the primary filtration by the sand removal louvers is divided into two paths: one path enters the air conditioning unit 14, is further filtered by the first fresh air section 1, the first primary efficiency filtration section 2 and the first medium efficiency filtration section 3 to form clean air, and then is cooled by the surface cooling section 4 and pressurized by the fan section 5; the other path enters the frequency converter fan box 15, is further filtered by the second fresh air section 6, the second primary efficiency filtration section 7 and the second medium efficiency filtration section 8 to form clean air, and then is pressurized by the frequency converter fan section 9; the air after the processing of the air conditioning unit 14 and the frequency converter fan box 15 is sent to the indoor working area through the air pipe and the air supply outlet 10, and the air volume G1 is 62400m 3 / h, and the supply air temperature ts1 is 28.0℃ under the summer design condition.

[0082] The mixed air after the mixing of the supply air and the backflow air in the high-temperature area has a temperature of tn=35℃. Under the action of the frequency converter 24 exhaust fan 25, the mixed air enters the frequency converter 24 cabinet through the inlet louvers, is heat-exchanged, and is then discharged to the high-temperature area by the exhaust fan 25, and has a temperature of tp=40.9℃. Part of the air entering the high-temperature area is discharged to the outdoor area through the air pipe and the exhaust outlet 11 under the action of the fan 21 and the frequency converter fan 23, and the other part of the air is mixed with the supply air.

[0083] When the outdoor air temperature is higher than 28.0°C, the air conditioning unit 14 and the variable frequency fan box 15 work simultaneously, the surface cooling section 4 of the air conditioning unit 14 is opened, and the temperature tn of the indoor working area is maintained at 35°C; the refrigerating capacity is only 88kW to compensate the cold load caused by the temperature difference between the outdoor air temperature tw and the supply air temperature ts1. The air conditioning unit 14, the variable frequency fan box 15, the fan 21 and the variable frequency fan 23 all work at the maximum air volume 62400m 3 / h designed.

[0084] When the outdoor temperature is lower than the supply air temperature 28.0°C, the air conditioning unit 14, the variable frequency fan box 15, the fan 21 and the variable frequency fan 23 all work simultaneously, but the surface cooling section 4 stops refrigeration, the variable frequency fan box 15 and the variable frequency fan 23 gradually reduce the ventilation volume through frequency adjustment, and the temperature tn of the indoor working area is maintained at 35°C; with the further reduction of the outdoor temperature, the air conditioning unit 14 and the fan 21 will stop working, only the variable frequency fan box 15 and the variable frequency fan 23 work simultaneously, and the frequency is adjusted, but cannot be less than the minimum frequency of the single machine.

[0085] When the winter design condition is reached, the variable frequency fan box 15 and the variable frequency fan 23 all work at the minimum frequency air volume 18720m 3 / h, in order to prevent the indoor temperature from being too low, the variable frequency fan 23 will mix part of the exhaust air with the outdoor fresh air through the bypass air pipe, and then send it into the indoor through the variable frequency fan box 15, to maintain the temperature tn (still tentatively 35°C) of the indoor working area, the bypass air volume G3=7600m 3 / h, which is adjusted by the opening degree of the electric valve MD7.

[0086] The first valve 16 and the second valve 17 are opened and closed with the air conditioning unit 14, the third valve 18 and the fourth valve 19 are opened and closed with the variable frequency fan box 15, the fifth valve 20 is opened and closed with the fan 21, and the sixth valve 22 is opened and closed with the variable frequency fan 23.

[0087] For this system, there is a certain standby relationship between the air conditioning unit 14 and the variable frequency fan box 15, and there is also a certain standby relationship between the fan 21 and the variable frequency fan 23. Once one of the devices fails, the other can still meet 50% of the air supply or exhaust volume, and the insufficient or excess air volume can be temporarily supplemented or removed by the penetration of doors and windows, thereby enhancing the reliability of the system.

[0088] First, the system fully combines the characteristics of the indoor temperature of the frequency converter, the temperature of the air outlet tp=40.9℃ is the exhaust temperature, and tn=35℃ is the indoor working area control temperature, which undoubtedly increases the exhaust temperature difference by 5.9℃, greatly reducing the demand for exhaust volume. Second, with the help of the direct expansion type air conditioning unit, the cold load of 88kW caused by the temperature difference between the outdoor air temperature tw=32.2℃ and the supply air temperature ts1=28℃ is supplemented, which is less than 1 / 3 of the equipment heat, and the operation time is very limited. Compared with the single unit air conditioning cooling mode, it has great energy saving potential, and the preliminary estimate of the annual energy saving rate is more than 40%. Finally, the air supplement equipment used in the system is composed of three-stage filtration, which greatly improves the cleanliness of the indoor environment of the frequency converter compared with the full direct current exhaust cooling mode, and at the same time, reduces the requirement for the net height of the civil construction; if the scheme is slightly more reasonable, and the way of half mechanical air supply and half natural air supply is adopted, the latter is not superior in initial investment and system energy consumption. In summary, the system, especially some non-coastal areas, has strong application prospect and technical advantage. The cost situation is estimated in the following table.

[0089]

[0090] Basic input

[0091] a. Meteorological parameters: summer air conditioning outdoor calculated dry bulb temperature tw1=32.2℃, summer air conditioning outdoor calculated wet bulb temperature tw2=21.5℃, winter air conditioning outdoor calculated dry bulb temperature tw3=-19.3℃ (note: here in order to increase the system application range, the winter ventilation outdoor calculation temperature is not adopted).

[0092] b. Indoor design requirements: design control temperature range 5-35℃, take summer indoor design temperature tn1=35℃; winter indoor design temperature tn2=35℃, but the minimum supply air temperature should not be lower than 5℃, in order to prevent part of the supply air from directly entering the frequency converter cabinet due to uneven air flow.

[0093] c. Basic information of the envelope structure: length 27m, width 16m, room area 432m 2 , net height H=5.6m, see attached Figure 2 ; thermal parameters: external wall heat transfer coefficient 0.56W / m2·℃, external window heat transfer coefficient 2.7W / m2·℃.

[0094] d. Basic information of the frequency converter: 8 frequency converters are arranged indoors, the heat dissipation of a single frequency converter is 31kW, the air volume of the fan of the frequency converter is 15600m 3 / h, the number of 8 frequency converters running simultaneously, indoor arrangement see attached Figure 2 . The indoor cooling load caused by the heat gain of the envelope structure and light is 23kW (estimated according to 50W / m 2 ).

[0095] S1: Calculate the frequency converter body air outlet temperature tp: Take the frequency converter inlet air temperature as the working zone temperature tn1=35℃, and from formula 1, tp=(31*8)*1000 / 1.2 / 0.28 / (15600*8)+35=40.9℃.

[0096] Formula 1:

[0097] Q=0.28c p ρ wn G(t out -t in )

[0098] Q: Indoor heat load, approximately equal to the total heat dissipation of the frequency converter W;

[0099] c p : Specific heat capacity of air at constant pressure, c p =1kJ / (kg·℃);

[0100] ρ wn : Air density at the inlet air calculation temperature, approximately 1.2 kg / m 3 ;

[0101] G: Ventilation quantity (m 3 / h);

[0102] t in : Inlet air temperature ℃

[0103] t out : Outlet air temperature ℃

[0104] Calculate the outdoor air conditioning dew point temperature tl: which can be obtained by using the psychrometric chart. In this paper, the psychrometric chart is drawn by using professional software T20 Tianzheng HVAC software V3.0 (see Figure 4 ) and tl=18.8℃ is obtained.

[0105] Determine the comparison between the frequency converter body air outlet temperature and the design meteorological parameters. If the frequency converter body air outlet temperature is greater than or equal to the design meteorological parameters, proceed to S2, otherwise directly use the air conditioner;

[0106] tp=40.9℃, tl=18.8℃, proceed to S2.

[0107] S2: Calculate the total heat Q2 of the frequency converter and the total ventilation quantity G2 of the frequency converter fan;

[0108] Q2=31*8=248kW

[0109] G2=15600*8=124800m 3 / h

[0110] S3: Calculate the percentage k1 of the total ventilation volume G2 of the frequency converter body by the ventilation volume G1 of the system design, and calculate the supply air temperature ts1 of the summer make-up air system. When ts1>tl, proceed to S4, otherwise adjust k1 and proceed to step S3;

[0111] Assuming k1=25%, then G1=0.25G2=0.25*124800=31200m 3 / h, and the excluded heat is Q1=0.25Q2. According to formula 1, ts1=35-[248*(1-0.25)+23]*1000 / 1.2 / 0.28 / 31200=15.1℃, which is less than tl=18.8℃, and k1 needs to be adjusted.

[0112] Assuming k1=40%, then G1=0.4G2=0.4*124800=49920m 3 / h, and the excluded heat is Q1=0.4Q2. According to formula 1, ts1=35-[248*(1-0.4)+23]*1000 / 1.2 / 0.28 / 49920=24.8℃, which is greater than tl=18.8℃;(A)

[0113] Assuming k1=50%, then G1=0.5G2=0.5*124800=62400m 3 / h, and the excluded heat is Q1=0.5Q2. According to formula 1, ts1=35-[248*(1-0.5)+23]*1000 / 1.2 / 0.28 / 62400=28℃, which is greater than tl=18.8℃;(B)

[0114] S4: Calculate the supply air temperature ts2 of a single air conditioner,

[0115] The supply air equipment is set to two, each bearing 50% of the supply air volume. From an economic point of view, when one device can meet the demand, the other device does not need to be set to refrigerate. Based on this, under the condition of permission, (B) is preferred, and (A) is the second choice; but in order to complete the example, the operation process of (A) and (B) is demonstrated respectively.

[0116] (A) The system design refrigeration capacity Q1=0.28*1.2*G1*(tw1-ts1) / 1000=0.28*1.2*(0.4*124800)*(32.2-24.5) / 1000=125kW;

[0117] (A) Take the rated refrigeration capacity Q3 of a single air conditioner Q1, then tS2=32.2-125*1000 / 1.2 / 0.28 / (0.5*0.4*124800)=17.3℃;

[0118] (A) tS2 = 17.3 °C is less than tl = 18.8 °C;

[0119] (A) The single air supply has dew condensation phenomenon, and two air conditioners are needed to work simultaneously. The rated cooling capacity of the single air conditioner Q3 = 0.5Q1 = 0.5*125 = 62 kW, and considering the 0.1 rich coefficient, Q3 finally takes 69 kW. The rated air volume of the equipment G5 = 0.5G1 = 0.5*(0.4*124800) = 24960 m 3 / h, and considering the 0.1 rich coefficient, G5 finally takes 27500 m 3 / h.

[0120] (B) The system design cooling capacity Q1 = 0.28*1.2*G1*(tw1-ts1) / 1000 = 0.28*1.2*(0.5*124800)*(32.2-28) / 1000 = 88 kW;

[0121] (B) The rated cooling capacity of the single air conditioner Q3 = Q1, then tS2 = 32.2-88*1000 / 1.2 / 0.28 / (0.5*0.5*124800) = 23.8 °C;

[0122] (B) tS2 = 23.8 °C is greater than tl = 18.8 °C;

[0123] (B) The single air supply has no dew condensation phenomenon, and the single equipment cooling can meet the system demand; The rated cooling capacity of the single air conditioner Q3 = Q1 = 88 kW, and the other air supply equipment does not cool. The rated air volume of the equipment G5 = 0.5G1 = 0.5*(0.5*124800) = 31200 m 3 / h. Note: The rich coefficient needs to be considered when selecting, which is not considered here.

[0124] The following solves the winter working condition, taking (B) as an example.

[0125] Indoor design requirements: design temperature 5-35 °C, winter indoor design temperature selected 35 °C will undoubtedly adopt smaller air supply than 5 °C, more conducive to energy saving and improving the application range of the system, therefore, the winter indoor design temperature tn2 = 35 °C; But the minimum air supply temperature should not be lower than 5 °C, to prevent uneven air flow from directly entering the frequency converter cabinet, therefore, the minimum value of the winter air supply system air supply temperature tsmin = 5 °C. Based on this, the winter system minimum air volume G4, the winter air supply temperature ts3 and the maximum bypass air volume G3 are calculated.

[0126] The indoor heat load caused by the envelope structure is 23 kW (according to 50 W / m 2 estimated)

[0127] kmin: the lower limit of the ratio of the minimum and maximum air volume of the variable frequency fan is 60%, provided by the manufacturer;

[0128] Minimum ventilation volume of the system in winter G4 = (248-23) * 1000 / 0.28 / 1.2 / [40.9-(-19.3)] = 11134 m 3 / h

[0129] Calculate the ratio of the minimum and maximum air volume of the variable frequency fan k2 = G4 / G5 = 11134 / 31200 = 35.7%

[0130] Since K2 is less than kmin, G4 needs to be increased. According to the value of kmin, G4 = kmin * G5 = 0.6 * 31200 = 18720 m

[0131] / h 3 / h

[0132] Calculate the winter supply air temperature ts3 = 40.9 - (248-23) * 1000 / 0.28 / 1.2 / 18720 = 5.1℃, which is greater than tsmin = 5℃

[0133] Calculate the maximum bypass air volume G3:

[0134] ts3 = 5.1℃ is greater than tw3 = -19.3℃, so the bypass air volume needs to be calculated. The bypass air volume is a simple mixing process, and the calculation formula is as follows:

[0135] G3 * tp + (G4-G3) * tw3 = G4 * ts3

[0136] G3 = G4 * (ts3-tw3) / (tp-tw3) = 18720 * [5.1-(-19.3)] / [40.9-(-19.3)] = 7600 m 3 / h

[0137] Output:

[0138] Sand removal louvers: 62400 m 3 / h(G1)

[0139] Air conditioning unit 14: composed of fresh air section, primary filter section, medium efficiency filter section, cooling section, fan section, 31200 m 3 / h(G5), refrigerating capacity 88kW(Q3)

[0140] Variable frequency fan box 15: composed of fresh air section, primary filter section, medium efficiency filter section, fan section, 18720-31200 m 3 / h(G4-G5)

[0141] Fan 21: 31200 m 3 / h (G5)

[0142] Variable frequency blower 23: 18720 ~ 31200 m 3 / h (G4 ~ G5)

[0143] Seventh valve 26: adjustment range 0 ~ 7600 x 1.1 m 3 / h (G3)

[0144] The above only the preferred embodiments of the present application, and not to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, should be included within the scope of the present application.

Claims

1. A method for using a variable frequency drive room air conditioning and ventilation coupled cooling system, characterized in that: The method comprises the following steps: S1: calculating the temperature tp of the air outlet of the frequency converter body, calculating the design dew point temperature tl of the outdoor air conditioner, and determining whether the temperature tp of the air outlet of the frequency converter body is greater than or equal to the design meteorological parameter; if yes, S2 is performed; S2: calculating the total heat Q2 of the frequency converter and the total air volume G2 of the fan of the frequency converter; S3: calculating the percentage k1 of the total air volume G2 of the frequency converter body and the system design air volume G1, and calculating the summer air supply temperature ts1; if ts1 is greater than or equal to tl, S4 is performed; otherwise, k1 is adjusted, and S3 is performed; S4: calculating the rated cooling capacity Q3 of the equipment and the rated air volume G5 of the equipment; S5: calculating the winter minimum air volume G4 of the system, and calculating the ratio k2 of the winter minimum air volume G4 of the system and the rated air volume G5 of the equipment of the frequency converter; S6: if k2 is greater than or equal to the lower limit kmin of the minimum and maximum air volume ratio of the frequency converter, the winter air supply temperature ts3 is calculated; otherwise, G4 is adjusted, and S5 is performed; S7: if ts3 is less than the minimum winter air supply temperature tsmin of the air supply system, G4 is adjusted, and S5 is performed; if ts3 is greater than or equal to the winter outdoor air conditioner related dry bulb temperature tw3, the maximum bypass air volume output result is calculated; otherwise, the design air volume G1, the rated air volume G5 of the equipment, the rated cooling capacity Q3 of the equipment, and the minimum air volume G4 of the system are directly output.

2. The use of a variable frequency converter room air conditioner and ventilation coupling cooling system according to claim 1, characterized in that: The calculation method of the maximum bypass air volume G3 in the step S7 is as follows: G3=G4*(ts3-tw3) / (yp-tw3) G3 is the maximum bypass air volume; G4 is the minimum air volume of the system; ts3 is the winter air supply temperature of the air supply system; tw3 is the winter outdoor air conditioner calculated dry bulb temperature; tp is the high temperature zone temperature.

3. The system of claim 1-2, wherein the system is used in the method of using a variable frequency inverter room air conditioning and ventilation coupling cooling system, characterized in that: The device comprises a sand removing device, an air conditioning unit (14), a frequency converter chamber, and a frequency converter fan box (15), The outdoor fresh air is connected with the first sand removing device (12) and the second sand removing device (13) through pipelines, the first sand removing device (12) is connected with the air conditioning unit (14) through a pipeline, The second sand removing device (13) is connected with the frequency converter fan box (15) through a pipeline, the air conditioning unit (14) and the frequency converter fan box (15) are connected with the frequency converter chamber through pipelines, the frequency converter chamber is connected with a first air exhaust assembly and a second air exhaust assembly, the first air exhaust assembly is connected with the outdoor, and the second air exhaust assembly is connected with the frequency converter fan box (15).

4. The variable frequency converter room air conditioning and ventilation coupling cooling system according to claim 3, characterized in that: The air conditioning unit (14) is connected with the outdoor fresh air through a first pipeline, the first sand removing device (12) is arranged on the first pipeline, a first valve (16) is arranged on the first pipeline, and the first valve (16) is arranged between the first sand removing device (12) and the air conditioning unit (14); The air conditioning unit (14) is connected with the frequency converter chamber through a second pipeline, and a second valve (17) is arranged on the second pipeline; The frequency converter fan box (15) is connected with the outdoor fresh air through a third pipeline, the second sand removing device (13) is arranged on the third pipeline, a third valve (18) is arranged on the third pipeline, and the third valve (18) is arranged between the second sand removing device (13) and the frequency converter fan box (15); The frequency conversion fan box (15) is connected with the frequency converter chamber through a fourth pipeline, and a fourth valve (19) is arranged on the fourth pipeline.

5. The variable frequency condenser room air conditioning and ventilation coupling cooling system according to claim 3, characterized in that: The frequency converter chamber is connected with a first exhaust assembly through a fifth pipeline, a fifth valve (20) is arranged on the fifth pipeline, the first exhaust assembly comprises a fan (21), the fan (21) is arranged on the fifth pipeline, and the fifth pipeline exhausts to the outside, The frequency converter chamber is connected with a second exhaust assembly through a sixth pipeline, a sixth valve (22) is arranged on the sixth pipeline, and the second exhaust assembly comprises a frequency conversion fan (23), the frequency conversion fan (23) is arranged on the sixth pipeline. The sixth pipeline is connected with the frequency conversion fan box (15) through a bypass pipeline, and the sixth pipeline is communicated with the outside. A seventh valve (26) is arranged on the bypass pipeline.

6. The variable frequency condenser room air conditioning and ventilation coupling cooling system according to claim 3, characterized in that: The air conditioning unit (14) is composed of a first fresh air section (1), a first primary filter section (2), a first medium-efficiency filter section (3), a surface cooling section (4) and a fan section (5), and the frequency conversion fan box (15) is composed of a second fresh air section (6), a second primary filter section (7), a second medium-efficiency filter section (8) and a frequency conversion fan section (9).

7. The inverter room air conditioning and ventilation coupling cooling system according to claim 6, characterized in that: The frequency converter chamber comprises a plurality of frequency converters (24), the top of each frequency converter (24) is provided with an exhaust fan (25), and the second pipeline and the fourth pipeline are connected with the first merging pipeline through a tee joint.

8. The variable frequency condenser room air conditioning and ventilation coupling cooling system according to claim 7, characterized in that: A plurality of air supply openings (10) are arranged on the first merging pipeline, the air supply openings (10) are arranged on the frequency converter chamber, and outdoor air is supplied to the lower part of the frequency converter (24).

9. The inverter room air conditioning and ventilation coupling cooling system according to claim 6, characterized in that: The fifth pipeline and the sixth pipeline are connected with a second merging pipeline through a tee joint, a plurality of exhaust openings (11) are arranged on the second merging pipeline, and the exhaust openings (11) are arranged above the frequency converter chamber.

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