A design method of a medium-temperature cold water centralized air conditioning system

Abstract

This invention relates to a design method for a medium-temperature chilled water centralized air conditioning system, belonging to the field of energy-saving air conditioning system design technology, and filling the gap in existing technologies for design methods of medium-temperature chilled water centralized air conditioning systems. The design method includes the following steps: S1, initial data extraction and initial judgment: determining whether adjustments to the selection and design of conventional fresh air handling units and fan coil units are needed; S2, calculating the indoor heat-to-moisture ratio and determining the air supply state point; S3, calculating the dehumidification capacity of the fresh air handling unit and fan coil units; S4, setting equipment selection parameters; S5, evaluating the dehumidification capacity of the fresh air handling unit; S6, evaluating the dehumidification capacity of the fan coil units; S7, determining the system supply water temperature. This invention can design medium-temperature chilled water centralized air conditioning systems with different operating conditions and determined supply water temperatures for different climate zones. Compared with normal temperature systems (7 / 12℃), the medium-temperature system has a higher evaporation temperature of the chiller unit, which can improve the system COP and achieve energy saving in air conditioning.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving air conditioning system design technology, specifically a design method for a medium-temperature chilled water centralized air conditioning system. Background Technology

[0002] In the field of heating, ventilation, and air conditioning in civil buildings, the design requirements for air conditioning chilled / hot water and condensate systems are clearly stipulated in the "Code for Design of Heating, Ventilation, and Air Conditioning in Civil Buildings" GB50736-2012. It states that if the supply water temperature of a chiller unit's direct cooling system is below 5℃, it will lead to poor operating conditions and insufficient stability. Meanwhile, to reduce pump power consumption and pipe diameter, large temperature difference designs are widely adopted. However, it should be noted that when using a large temperature difference design, if the average water temperature of the terminal equipment is required to remain essentially constant, the outlet water temperature of the chiller unit needs to be reduced, resulting in a decrease in its coefficient of performance (COP). Furthermore, large temperature difference designs also require verification of the impact of flow reduction on the heat transfer coefficient and heat transfer of the terminal equipment; if necessary, the specifications of the terminal equipment need to be increased. Currently, the national standard operating conditions for relevant refrigeration equipment are based on a supply water temperature of 7℃ and a return water temperature of 12℃, which has become the standard condition in the design of centralized air conditioning systems. For many years, the supply and return water temperatures of 7℃ / 12℃ have been used as the standard design conditions in the design of centralized air conditioning systems. In the optimization design, large temperature difference designs (such as 5℃ / 12℃, 6℃ / 13℃, 7℃ / 14℃, etc.) are often used to reduce the energy consumption of transmission and distribution.

[0003] With the introduction of the "dual carbon" target, engineering design and operation are paying more attention to energy conservation and carbon reduction. Therefore, some unconventional water temperature design conditions are gradually emerging, such as a 10℃ / 15℃ supply and return water condition. In the actual operation of high-efficiency computer rooms, the supply water temperature is often controlled at 8-11℃ to improve the energy efficiency of the chiller units. However, because the design selection is still based on conventional chiller units, the design conditions remain at 7℃ / 12℃ supply and return water temperatures. Only by changing the operating conditions can some energy efficiency be improved, and the energy-saving effect of this approach is relatively limited.

[0004] Against this backdrop, replacing traditional ambient temperature water supply with medium temperature water supply (water temperature range of 9-15℃) has become a key measure to improve the annual energy efficiency of chilled water and air conditioning systems. However, as a relatively new technology, research on medium temperature chilled water centralized air conditioning systems mainly focuses on the system operation level. For example, existing technologies have proposed comprehensive performance evaluation methods for medium temperature chilled water centralized air conditioning systems, or disclosed time-series prediction models based on Long Short-Term Memory (LSTM) networks and multi-scale attention mechanisms for unit power consumption prediction.

[0005] In summary, for dedicated chiller units operating under medium-temperature water conditions, the existing design methods are insufficient to meet the new energy-saving and carbon-reduction requirements due to the fact that these units are no longer operating under the standard conditions of the past. In addition, given my country's vast territory, diverse building climate zones, and significant differences in outdoor environmental conditions, the specific design methods for centralized air conditioning systems for medium-temperature chilled water, especially the setting of supply water temperature, are still in a blank stage. This has led to the current equipment selection still being based on conventional chilled water supply and return water temperatures of 7℃ / 12℃, which seriously restricts the achievement of energy-saving and carbon-reduction goals.

[0006] Therefore, there is an urgent need for a design method for a medium-temperature chilled water centralized air conditioning system that can adapt to the design conditions of different climate zones and determine the water supply temperature, so as to achieve efficient operation of the entire centralized air conditioning system throughout the year while meeting the requirements of comfort air conditioning use. Summary of the Invention

[0007] This invention addresses the shortcomings of existing design methods for medium-temperature chilled water centralized air conditioning systems, such as the lack of scientific basis for setting the water supply temperature and the mismatch between equipment selection and actual operating requirements. To address these shortcomings, the following technical solution is adopted to achieve the design of energy-saving air conditioning equipment or energy-saving heat exchange devices, as well as high energy efficiency:

[0008] A design method for a medium-temperature chilled water centralized air conditioning system includes the following steps:

[0009] S1. Initial data extraction and initial judgment: Determine whether the selection and design of conventional fresh air handling units and fan coil units need to be adjusted;

[0010] S2. Calculate the indoor heat-to-moisture ratio and determine the air supply state point;

[0011] S3. Calculate the dehumidification capacity of the fresh air handling unit and fan coil unit;

[0012] S4. Equipment selection parameter setting;

[0013] S5. Evaluation of the dehumidification capacity of the fresh air handling unit;

[0014] S6. Evaluation of the dehumidification capacity of fan coil units;

[0015] S7. System water supply temperature is determined.

[0016] Furthermore, the initial data extraction and initial judgment in S1 specifically include the following steps:

[0017] S11. Extract the calculated dry-bulb temperature and wet-bulb temperature of the outdoor air conditioner; extract the indoor design operating temperature and relative humidity.

[0018] S12. Further determine the outdoor air humidity and indoor air humidity using the enthalpy-humidity chart;

[0019] S13. Determine whether it is necessary to adjust the selection and design of conventional fresh air handling units and fan coil units.

[0020] Furthermore, S13 determines whether the selection and design of the conventional fresh air handling unit and fan coil unit need to be adjusted. Specifically, it is determined whether the outdoor air humidity is greater than the indoor air humidity. If the outdoor air humidity is not greater than the indoor air humidity, then there is no need to adjust the selection and design of the conventional fresh air handling unit and fan coil unit. The water supply temperature is directly set to 15℃, and the terminal coil and other equipment are directly selected. Otherwise, S2 is continued to calculate the indoor heat-moisture ratio to determine the air supply state point.

[0021] Furthermore, the S3 calculation of the dehumidification capacity of the fresh air handling unit and fan coil unit specifically includes the following steps:

[0022] S31. Calculate the dehumidification capacity of the fresh air handling unit;

[0023] S32. Calculate the dehumidification capacity of the fan coil unit.

[0024] Furthermore, the calculation of the dehumidification capacity of the fresh air handling unit in step S31 specifically includes the following steps:

[0025] Calculate the theoretical dehumidification capacity Δd X =d W -d LX , where d LX It is the moisture content of indoor air after dehumidification by the fresh air handling unit, specifically the moisture content at point L determined by the isenthalpic or isohumid curve of the indoor air after fresh air treatment. LX .

[0026] Furthermore, the calculation of the fan coil unit's dehumidification capacity in step S32 specifically includes the following steps:

[0027] Calculate the enthalpy h at the fan coil unit outlet based on the total air volume and the fresh air volume. M Connect L and O and extend with enthalpy h M The intersection points are determined, and the intersection point M is obtained. The moisture content at point M is then d. M Therefore, the dehumidification capacity of the fan coil unit can be calculated as Δd. P =d N -d M .

[0028] Furthermore, the S4 device selection parameter setting specifically includes the following steps:

[0029] Set the number of fresh air handling unit manufacturers to m, and sort them in ascending order of dehumidification capacity. Set X... i For fresh air handling unit manufacturers, the value range of the serial number i is 1 to m;

[0030] Let there be n fan coil unit manufacturers, sorted by dehumidification capacity from lowest to highest, and let P be the dehumidification capacity of the equipment. j For fan coil unit manufacturers, the value range of the serial number j is 1 to n;

[0031] Set the water supply temperature t of the fresh air handling unit xga =a, whose value ranges from 10℃ to 15℃, and the water supply temperature t of the fan coil unit. pgb =b, and its value ranges from 10℃ to 15℃.

[0032] Furthermore, the dehumidification capacity assessment of the S5 fresh air handling unit specifically includes the following steps:

[0033] First, set the initial parameters: the initial value of the fresh air unit manufacturer's serial number is i=1, and the corresponding initial value of the water supply temperature is a=15 (i.e., the highest medium-temperature chilled water temperature of 15℃, to ensure the highest efficiency; to meet the medium-temperature chilled water operating conditions, the value range of a is set to 10-15℃).

[0034] Then, based on the equipment parameters provided by all m fresh air handling unit manufacturers, the corresponding fresh air handling unit manufacturer X is extracted sequentially when the water supply temperature is a. i The maximum dehumidification capacity Δd1 for the 4-row pipe equipment, the maximum dehumidification capacity Δd2 for the 6-row pipe equipment, and the maximum dehumidification capacity Δd3 for the 8-row pipe equipment.

[0035] Determine the theoretical dehumidification capacity Δd sequentially X With the fresh air unit manufacturer X i The relationship between the maximum dehumidification capacities Δd1, Δd2, and Δd3 of different devices is used to determine the maximum water supply temperature t. g1 Corresponding fresh air handling unit manufacturer X i Corresponding equipment selection.

[0036] Furthermore, the evaluation of the dehumidification capacity of the S6 fan coil unit specifically includes the following steps:

[0037] First, set the initial parameters: the initial value of the fan coil unit manufacturer's serial number is j=1, and the corresponding initial value of the water supply temperature is b=15 (i.e., the highest medium-temperature chilled water temperature of 15℃, to ensure the highest efficiency; to meet the medium-temperature chilled water operating conditions, the value range of b is set to 10-15℃).

[0038] Then, based on the equipment parameters provided by all n fan coil unit manufacturers, extract the corresponding fan coil unit manufacturer P when the water supply temperature is b, in sequence. j The maximum dehumidification capacity of the 2-row pipe equipment is Δd4, the maximum dehumidification capacity of the 3-row pipe equipment is Δd5, and the maximum dehumidification capacity of the 4-row pipe equipment is Δd6.

[0039] Determine the theoretical dehumidification capacity Δd sequentiallyP With the fan coil unit manufacturer P j The relationship between the maximum dehumidification capacities Δd4, Δd5, and Δd6 of different devices is used to determine the maximum water supply temperature t. g2 The corresponding fan coil unit manufacturer P j Corresponding equipment selection.

[0040] Furthermore, the determination of the water supply temperature of the S7 system specifically includes the following steps:

[0041] Based on the highest water supply temperature tg1 obtained from the dehumidification capacity assessment of the S5 fresh air handling unit and the highest water supply temperature tg2 obtained from the dehumidification capacity assessment of the S6 fan coil unit, determine the magnitude of the two and take the lower water supply temperature as the system's water supply temperature tg.

[0042] This invention can achieve at least one of the following beneficial effects:

[0043] (1) This invention proposes a specific design method for a medium-temperature chilled water centralized air conditioning system, filling the gap in the existing technology for medium-temperature system design methods. It can design a medium-temperature chilled water centralized air conditioning system for different outdoor design conditions (climate zones) and determine the water supply temperature. Compared with the normal temperature system (7 / 12℃), the medium-temperature system has a higher evaporation temperature, which can improve the system COP (Coefficient of Performance). It also reduces the risk of mold growth in condensate. At the same time, it is easy to combine with frequency conversion technology and natural cold sources, such as free cooling towers. The efficiency advantage is more obvious in transitional seasons or low loads. Furthermore, the final determination of the system water supply temperature takes into account the dehumidification capacity of the fresh air unit and fan coil unit, which can ensure the efficient operation of the entire system under medium-temperature water conditions.

[0044] (2) By adding the judgment of the dehumidification capacity of equipment from different manufacturers, there is no need to sort the equipment. When multiple equipment meet the dehumidification capacity, the highest medium-temperature chilled water supply temperature and the corresponding manufacturer equipment can be obtained, thereby improving the cooling efficiency. Furthermore, the manufacturer parameters can be continuously expanded during the design process to improve design efficiency.

[0045] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the specification or be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained from the content specifically pointed out in the text and accompanying drawings. Attached Figure Description

[0046] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0047] Figure 1 This is a flowchart illustrating the design method for a centralized air conditioning system with medium-temperature chilled water proposed in Embodiment 1 of the present invention.

[0048] Figure 2 This is a flowchart illustrating the design method for a medium-temperature chilled water centralized air conditioning system proposed in Embodiment 2 of the present invention. Detailed Implementation

[0049] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0050] Example 1:

[0051] This invention provides a design method for a medium-temperature chilled water centralized air conditioning system, specifically including the following steps:

[0052] S1 Initial Data Extraction and Initial Judgment: Determine whether the selection and design of conventional fresh air handling units and fan coil units need to be adjusted;

[0053] S2 calculates the indoor heat-to-moisture ratio and determines the air supply state point;

[0054] S3 calculates the dehumidification capacity of fresh air handling units and fan coil units;

[0055] S4 equipment selection parameter settings;

[0056] Assessment of the dehumidification capacity of the S5 fresh air handling unit;

[0057] Evaluation of the dehumidification capacity of S6 fan coil units;

[0058] The water supply temperature of the S7 system is determined.

[0059] The following is a detailed explanation of each step:

[0060] S1 initial data extraction and initial judgment specifically include the following steps:

[0061] S11: Based on the "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings" or local meteorological data, extract the outdoor air conditioning dry-bulb temperature t. Wg Calculate the wet-bulb temperature t of the outdoor air conditioner Ws Based on the application scenarios and user needs of the medium-temperature chilled water centralized air conditioning system, the indoor design operating temperature t is extracted. N and relative humidity

[0062] S12 further determines the outdoor air humidity d using an enthalpy-humidity chart. W Indoor air humidity d N ;

[0063] S13 determines whether adjustments to the selection and design of conventional fresh air handling units and fan coil units are needed, specifically by judging the outdoor air humidity content d. W Is it greater than the indoor air humidity level d? N If the outdoor air humidity is d W Not greater than the indoor air humidity d N If the selection and design of conventional fresh air handling units and fan coil units are not adjusted, the water supply temperature can be directly set to 15℃, and the selection of terminal coils and other equipment can be carried out directly; otherwise, continue to calculate the indoor heat-moisture ratio using S2 to determine the air supply state point.

[0064] By extracting initial data and making initial judgments, corresponding designs can be made for different regions and climate conditions. At the same time, the water supply temperature under different regions and climate conditions can be preliminarily judged. If the outdoor air humidity is not greater than the indoor air humidity, the highest temperature of medium-temperature cold water, 15℃, can be directly used for system design, avoiding subsequent complex calculations and selection design, and improving work efficiency.

[0065] S2 calculates the indoor heat-to-moisture ratio ε and determines the supply air state point O, specifically including the following steps:

[0066] S21 Calculation of Indoor Heat-Moisture Ratio ε: Indoor heat-moisture ratio ε refers to the indoor sensible heat load Q. s With latent heat load Q l The ratio of sensible heat load Q to sensible heat load Q reflects the direction and characteristics of the indoor air state change process. s This includes, but is not limited to, sensible heat components such as heat dissipation from personnel, equipment, and heat transferred through the building envelope. Latent heat load Q l The main sources include moisture emitted by personnel and moisture introduced by infiltrating air, which are calculated and determined based on actual operating conditions.

[0067] S22 Determine the air supply state point O: Determine the air supply point O based on the indoor heat-moisture ratio line on the enthalpy-humidity chart, using the intersection of the heat-moisture ratio line and 90% relative humidity;

[0068] The indoor design operating temperature t is marked on the enthalpy-humidity diagram. N and relative humidity For the indoor state point N, the heat-moisture ratio line is a straight line drawn along the ε direction with point N as the starting point. The angle θ between the heat-moisture ratio line and the isenthalpic line satisfies: tanθ=1 / ε.

[0069] S3 calculates the dehumidification capacity of fresh air handling units and fan coil units, specifically including the following steps:

[0070] S31 Calculates the dehumidification capacity of the fresh air handling unit: Calculates the theoretical dehumidification capacity Δd X =d W -d LX , where d LX This refers to the moisture content of indoor air after dehumidification by the fresh air handling unit. Specifically, it's the moisture content at point L, determined by the isenthalpic or isohumidity line of the indoor environment after fresh air treatment. Here, the intersection of the 90% relative humidity line is used as point L, and the moisture content at point L is d. LX If the fan temperature rises, the calculation will be based on the point after the temperature rise.

[0071] S32 Calculate the dehumidification capacity of the fan coil unit: Calculate the enthalpy hM at the fan coil unit outlet based on the total air volume and fresh air volume. Connect L and O and extend the line to intersect the enthalpy hM. Determine the intersection point M, and obtain the moisture content d at point M. M Therefore, the dehumidification capacity of the fan coil unit can be calculated as Δd. P =d N -d M .

[0072] The S4 equipment selection parameter setting includes the following steps:

[0073] Let there be m manufacturers of fresh air handling units, and sort them from lowest to highest dehumidification capacity, thus defining X. i There are m manufacturers of fresh air handling units, and the value range of the corresponding fresh air handling unit serial number i is 1 to m.

[0074] Let there be n fan coil unit manufacturers, sorted by their dehumidification capacity from lowest to highest. Let P be the dehumidification capacity of each manufacturer. j There are n fan coil unit manufacturers, and the corresponding fan coil unit manufacturer serial number j ranges from 1 to n.

[0075] Where m and n represent the number of fresh air handling unit manufacturers and fan coil unit manufacturers selected according to actual needs.

[0076] Set the water supply temperature t of the fresh air handling unit xga =a, whose value ranges from 10℃ to 15℃, and the water supply temperature t of the fan coil unit. pgb =b, whose value ranges from 10℃ to 15℃, thus ensuring that the system is designed for medium-temperature water conditions and can guarantee the efficient operation of the system.

[0077] The dehumidification capacity assessment of the S5 fresh air handling unit includes the following steps:

[0078] First, set the initial parameters: the initial value of the fresh air unit manufacturer's serial number is i=1, and the initial value of the water supply temperature is a=15 (i.e., the highest medium-temperature chilled water temperature is 15℃, to ensure the highest efficiency; to meet the medium-temperature chilled water operating conditions, the value of a is set to a range of 10-15℃).

[0079] Then, based on the equipment parameters provided by all m fresh air handling unit manufacturers, the corresponding fresh air handling unit manufacturer X is extracted sequentially when the water supply temperature is a. i The maximum dehumidification capacity Δd1 for the 4-row pipe equipment, the maximum dehumidification capacity Δd2 for the 6-row pipe equipment, and the maximum dehumidification capacity Δd3 for the 8-row pipe equipment.

[0080] Determine the theoretical dehumidification capacity Δd sequentially X With the fresh air unit manufacturer X i The relationship between the maximum dehumidification capacities Δd1, Δd2, and Δd3 of different devices is used to determine the maximum water supply temperature t. g1 Corresponding fresh air handling unit manufacturer X i Corresponding equipment selection.

[0081] Specifically, when making the judgment, that is, initially when i = 1 and a = 15, the judgment is made on Δd. X If ≤Δd1, then output t. g1 =a (i.e., 15℃), end the fresh air unit equipment selection, select the 4-row pipe equipment from manufacturer X1; otherwise, continue to judge Δd. X If the condition ≤Δd2 is met, then output t. g1 =a (i.e., 15℃), end the fresh air unit equipment selection, select the 6-row pipe equipment from manufacturer X1; otherwise, continue to judge Δd. X If ≤Δd3, then output t. g1 =a (i.e., 15℃), end the fresh air unit equipment selection, and select the 8-row pipe equipment from manufacturer X1; otherwise, it is determined that there is no equipment from that manufacturer that meets the requirements at the current temperature, and a is reduced step by step. Here, we take a step of 1℃ as an example, that is, let a = a-1 (i.e., a is 14℃), and repeat the above judgment. If it is satisfied, output t accordingly. g1 =14℃, and select manufacturer X1 to meet the theoretical dehumidification capacity Δd. X If no suitable equipment is available at the current temperature, the process continues until a reaches 10℃. If the manufacturer still cannot meet the theoretical dehumidification capacity Δd, the process is repeated. X The corresponding equipment will then step on i in increments of 1, i.e., select the second fresh air unit manufacturer X2, and repeat the above process for the highest water supply temperature t. g1 When selecting fresh air handling unit (FLU) equipment, if none of the FLU manufacturers meet the theoretical dehumidification capacity Δd... X Then directly set the highest water supply temperature t g1The temperature is set at 9℃, and the fresh air handling unit manufacturer is X. m We selected the manufacturer's 8-row pipe equipment.

[0082] By using this method of judgment, based on the prioritization of the equipment capabilities of fresh air handling unit manufacturers, the most suitable equipment for dehumidification can be selected quickly, and the highest medium-temperature chilled water supply temperature can be determined, thereby improving work efficiency.

[0083] The dehumidification capacity assessment of the S6 fan coil unit includes the following steps:

[0084] First, set the initial parameters: the initial value for the fan coil unit manufacturer's serial number is j=1, and the initial value for the water supply temperature is b=15 (i.e., the highest medium-temperature chilled water temperature is 15℃, ensuring the highest efficiency; to meet the medium-temperature chilled water operating conditions, the value of b is set to a range of 10-15℃).

[0085] Then, based on the equipment parameters provided by all n fan coil unit manufacturers, extract the corresponding fan coil unit manufacturer P when the water supply temperature is b, in sequence. j The maximum dehumidification capacity of the 2-row pipe equipment is Δd4, the maximum dehumidification capacity of the 3-row pipe equipment is Δd5, and the maximum dehumidification capacity of the 4-row pipe equipment is Δd6.

[0086] Determine the theoretical dehumidification capacity Δd sequentially P With the fan coil unit manufacturer P j The relationship between the maximum dehumidification capacities Δd4, Δd5, and Δd6 of different devices is used to determine the maximum water supply temperature t. g2 The corresponding fan coil unit manufacturer P j Corresponding equipment selection.

[0087] Specifically, during the judgment, i.e., initially when j=1 and b=15, the judgment is made regarding Δd. P If the condition is ≤Δd4, then output t. g2 =b (i.e., 15℃), end the fan coil unit selection process and select the 2-row pipe unit from manufacturer P1; otherwise, continue to judge Δd. P If ≤Δd5, output t. g2 =b (i.e., 15℃), end the fan coil unit selection process and select the 3-row pipe equipment from manufacturer P1; otherwise, continue to judge Δd. P If ≤Δd6, output t. g2 =b (i.e., 15℃), end the fan coil unit selection, and select the 4-row pipe equipment from manufacturer P1; otherwise, it is determined that there is no equipment from that manufacturer that meets the requirements at the current temperature, and b is reduced step by step. Here, we take a step of 1℃ reduction as an example, that is, let b = b-1 (i.e., b is 14℃), and repeat the above judgment. If the condition is met, the corresponding output t is output. g2 =14℃, and select manufacturer P1 to meet the theoretical dehumidification capacity Δd.P If no suitable equipment is available at the current temperature, the process continues until b reaches 10℃. If the manufacturer still cannot meet the theoretical dehumidification capacity Δd, the process is reversed. P The corresponding equipment will then step on j with a step interval of 1, that is, select the second fan coil unit manufacturer P2, and repeat the above process for the highest water supply temperature t. g2 When selecting fan coil unit manufacturers, if none of them meet the theoretical dehumidification capacity Δd... P Then directly set the highest water supply temperature t g2 The temperature is set to 9℃, and the fan coil unit manufacturer is P. n And select the manufacturer's 4-row pipe equipment.

[0088] By using this method of judgment, based on the prioritization of the equipment capabilities of fan coil unit manufacturers, the most suitable equipment for dehumidification can be selected quickly, and the highest medium-temperature chilled water supply temperature can be determined, thereby improving work efficiency.

[0089] Determining the water supply temperature for the S7 system involves the following steps:

[0090] Based on the highest water supply temperature t obtained from the dehumidification capacity assessment of the S5 fresh air handling unit. g1 And the highest supply water temperature t obtained from the dehumidification capacity assessment of the S6 fan coil unit. g2 Determine the magnitudes of the two values, and take the lower water supply temperature as the system's water supply temperature t. g .

[0091] Specifically, if t g1 ≥t g2 Then the system water supply temperature t g =t g2 Otherwise, the system water supply temperature t g =t g1 .

[0092] The design method for a medium-temperature chilled water centralized air conditioning system proposed in this invention fills the gap in existing technology for medium-temperature system design. Compared with the normal temperature system (7 / 12℃), the medium-temperature system has a higher evaporation temperature, which can improve the system's COP (Coefficient of Performance). It also reduces the risk of mold growth in condensate. Furthermore, it is easy to combine with variable frequency technology and natural cold sources, such as free cooling towers. Its efficiency advantage is more obvious during transitional seasons or low loads. The final determination of the system's water supply temperature takes into account the dehumidification capacity of the fresh air handling unit and fan coil units, which can ensure the efficient operation of the entire system under medium-temperature water conditions.

[0093] Example 2:

[0094] Based on Example 1, such as Figure 2 As shown, in order to improve the efficiency of equipment selection from different manufacturers and to optimize equipment selection when manufacturers' equipment capabilities overlap, this invention also proposes a technical solution for further optimizing the above-mentioned design method for a medium-temperature chilled water centralized air conditioning system, including the following main steps:

[0095] S1 Initial Data Extraction and Initial Judgment: Determine whether the selection and design of conventional fresh air handling units and fan coil units need to be adjusted;

[0096] S2 calculates the indoor heat-to-moisture ratio and determines the air supply state point;

[0097] S3 calculates the dehumidification capacity of fresh air handling units and fan coil units;

[0098] S4 equipment selection parameter settings;

[0099] Assessment of the dehumidification capacity of the S5 fresh air handling unit;

[0100] Evaluation of the dehumidification capacity of S6 fan coil units;

[0101] S7 system water supply temperature determination and manufacturer equipment selection results output.

[0102] The steps S1 (initial data extraction and initial judgment), S2 (calculation of indoor heat-to-moisture ratio and determination of air supply status point), and S3 (calculation of dehumidification capacity of fresh air unit and fan coil unit) are the same as in Example 1, and will not be repeated here.

[0103] Furthermore, the S4 equipment selection parameter setting specifically includes the following steps:

[0104] Let the number of fresh air handling unit manufacturers be m, and let X be the number of manufacturers. i There are m manufacturers of fresh air handling units, and the value range of the corresponding fresh air handling unit serial number i is 1 to m.

[0105] Let the number of fan coil unit manufacturers be n, and thus set P. j There are n fan coil unit manufacturers, and the corresponding fan coil unit manufacturer serial number j ranges from 1 to n.

[0106] Where m and n represent the number of fresh air handling unit manufacturers and fan coil unit manufacturers selected according to actual needs.

[0107] Set the water supply temperature t of the fresh air handling unit xga =a, whose value ranges from 10℃ to 15℃, and the water supply temperature t of the fan coil unit. pgb =b, whose value ranges from 10℃ to 15℃, thus ensuring that the system is designed for medium-temperature water conditions and can guarantee the efficient operation of the system.

[0108] The dehumidification capacity assessment of the S5 fresh air handling unit includes the following steps:

[0109] First, set the initial parameters: the initial value of the fresh air unit manufacturer's serial number is i=1, and the initial value of the water supply temperature is a=15 (i.e., the highest medium-temperature chilled water temperature is 15℃, to ensure the highest efficiency; to meet the medium-temperature chilled water operating conditions, the value of a is set to a range of 10-15℃).

[0110] Then, based on the equipment parameters provided by all m fresh air handling unit manufacturers, the corresponding fresh air handling unit manufacturer X is extracted sequentially when the water supply temperature is a. i The maximum dehumidification capacity Δd of the 4-row pipe equipment i1 The maximum dehumidification capacity Δd of the 6-row pipe equipment i2 The maximum dehumidification capacity Δd of the 8-row pipe equipment i3 .

[0111] Determine the theoretical dehumidification capacity Δd sequentially X With the fresh air unit manufacturer X i Maximum dehumidification capacity Δd of different devices i1 , Δd i2 and Δd i3 The size relationship determines the maximum water supply temperature t. gi1 Corresponding fresh air handling unit manufacturer X i Corresponding equipment selection.

[0112] Specifically, when making the judgment, that is, initially when i = 1 and a = 15, the judgment is made on Δd. X ≤Δd 11 If the condition is met, output t. g11 =a (i.e., 15℃), end the selection of fresh air handling unit equipment from manufacturer X1, select the 4-row pipe equipment from manufacturer X1, and proceed to the next manufacturer X2 for equipment selection; otherwise, continue to judge Δd. X ≤Δd 12 If the condition is met, output t. g11 =a (i.e., 15℃), end the selection of fresh air handling unit equipment from manufacturer X1, select the 6-row pipe equipment from manufacturer X1, and proceed to the next manufacturer X2 for equipment selection; otherwise, continue to judge Δd. X ≤Δd 13 If the condition is met, output t. g11 =a (i.e., 15℃), end the selection of fresh air handling unit equipment for manufacturer X1, select the 8-row pipe equipment of manufacturer X1, and proceed to the next manufacturer X2 for equipment selection; otherwise, it is determined that there is no equipment that meets the conditions at the current temperature, and a is reduced step by step. Here, we take a step of 1℃ as an example, that is, let a = a-1 (i.e., a is 14℃), and repeat the above judgment. If the condition is met, the corresponding output t is output. g11=14℃, and select manufacturer X1 to meet the theoretical dehumidification capacity Δd. X If no suitable equipment is available at the current temperature, the process continues until a reaches 10℃. If the manufacturer still cannot meet the theoretical dehumidification capacity Δd, the process is repeated. X The corresponding equipment will then step on i in increments of 1, i.e., select the second fresh air unit manufacturer X2, and repeat the above process for the highest water supply temperature t. g12 When selecting fresh air handling unit (FLU) equipment, if none of the FLU manufacturers meet the theoretical dehumidification capacity Δd... X Then directly set the highest water supply temperature t g1 The temperature is set at 9℃, and the fresh air handling unit manufacturer is X. m We selected the manufacturer's 8-row pipe equipment.

[0113] The dehumidification capacity assessment of the S6 fan coil unit includes the following steps:

[0114] First, set the initial parameters: the initial value for the fan coil unit manufacturer's serial number is j=1, and the initial value for the water supply temperature is b=15 (i.e., the highest medium-temperature chilled water temperature is 15℃, ensuring the highest efficiency; to meet the medium-temperature chilled water operating conditions, the value of b is set to a range of 10-15℃).

[0115] Then, based on the equipment parameters provided by all n fan coil unit manufacturers, extract the corresponding fan coil unit manufacturer P when the water supply temperature is b, in sequence. j The maximum dehumidification capacity Δd of the two-row pipe equipment j4 The maximum dehumidification capacity Δd of the 3-row pipe equipment j5 The maximum dehumidification capacity Δd of the 4-row pipe equipment j6 .

[0116] Determine the theoretical dehumidification capacity Δd sequentially P With the fan coil unit manufacturer P j Maximum dehumidification capacity Δd of different devices j4 , Δd j5 and Δd j6 The size relationship determines the maximum water supply temperature t. gj2 The corresponding fan coil unit manufacturer P j Corresponding equipment selection.

[0117] Specifically, during the judgment, i.e., initially when j=1 and b=15, the judgment is made regarding Δd. P ≤Δd 14 If the condition is met, output t. g21 =b (i.e., 15℃), end the selection of fan coil unit equipment from manufacturer P1, select the 2-row pipe equipment from manufacturer P1, and proceed to the next equipment selection from manufacturer P2; otherwise, continue to judge Δd. P ≤Δd15 If the condition is met, output t. g21 =b (i.e., 15℃), end the selection of fan coil unit equipment from manufacturer P1, select the 3-row pipe equipment from manufacturer P1, and proceed to the next equipment selection from manufacturer P2; otherwise, continue to judge Δd. P ≤Δd 16 If the condition is met, output t. g21 =b (i.e., 15℃), end the fan coil unit selection for manufacturer P1, select the 4-row pipe equipment from manufacturer P1, and proceed to the next equipment selection for manufacturer P2; otherwise, it is determined that there is no equipment from this manufacturer that meets the conditions at the current temperature, and b is reduced step by step. Here, we take a step of 1℃ as an example, that is, let b = b-1 (i.e., b is 14℃), and repeat the above judgment. If the condition is met, output t accordingly. g22 =14℃, and select manufacturer P1 to meet the theoretical dehumidification capacity Δd. P If no suitable equipment is available at the current temperature, the process continues until b reaches 10℃. If the manufacturer still cannot meet the theoretical dehumidification capacity Δd, the process is reversed. P The corresponding equipment will then step on j with a step interval of 1, that is, select the second fan coil unit manufacturer P2, and repeat the above process for the highest water supply temperature t. g2n When selecting fan coil unit manufacturers, if none of them meet the theoretical dehumidification capacity Δd... P Then directly set the highest water supply temperature t g2 The temperature is set to 9℃, and the fan coil unit manufacturer is P. n And select the manufacturer's 4-row pipe equipment.

[0118] The process of determining the S7 system water supply temperature and outputting the manufacturer's equipment selection results includes the following steps:

[0119] Based on the S5 fresh air handling unit's dehumidification capacity assessment, the highest corresponding water supply temperature t for all devices meeting the dehumidification capacity requirements was obtained. g1i Take all t g1i The maximum value in the range is taken as the highest water supply temperature t. g1 ;

[0120] Select the temperature corresponding to the highest water supply temperature t g1 The selection of fresh air handling unit manufacturers and their equipment based on the number of ducts is the final selection of fresh air handling unit;

[0121] Based on the S6 fan coil unit dehumidification capacity assessment, the highest corresponding water supply temperature t for all devices that meet the dehumidification capacity requirements is obtained. g2j Take all t g2j The maximum value in the range is taken as the highest water supply temperature t. g2 ;

[0122] Select the temperature corresponding to the highest water supply temperature tg2 The fan coil unit manufacturer and its equipment for the number of pipes are used as the final selection of fan coil unit equipment;

[0123] Determine the highest water supply temperature t g1 and the highest water supply temperature t g2 The values ​​of the two are considered, and the lower water supply temperature is taken as the system's water supply temperature t. g .

[0124] Specifically, if t g1 ≥t g2 Then the system water supply temperature t g =t g2 Otherwise, the system water supply temperature t g =t g1 .

[0125] By adding the assessment of dehumidification capacity for equipment from different manufacturers, there is no need to prioritize equipment selection. This solves the problem of obtaining the highest suitable medium-temperature chilled water supply temperature and corresponding manufacturer equipment when multiple devices meet the dehumidification capacity requirements, thereby improving cooling efficiency. Furthermore, the manufacturer parameters can be continuously expanded during the design process, improving design efficiency.

[0126] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A design method for a centralized air conditioning system for medium-temperature chilled water, characterized in that, Includes the following steps: S1. Initial data extraction and initial judgment: Determine whether the selection and design of conventional fresh air handling units and fan coil units need to be adjusted; S2. Calculate the indoor heat-to-moisture ratio and determine the air supply state point; S3. Calculate the dehumidification capacity of the fresh air handling unit and fan coil unit; S4. Equipment selection parameter setting; S5. Dehumidification capacity assessment of fresh air handling units: First, set the initial parameters: the initial value of the fresh air unit manufacturer's serial number is i = 1, and the corresponding initial value of the water supply temperature 'a' is set to a range of 10. 15℃; Then, based on the equipment parameters provided by all m fresh air handling unit manufacturers, the corresponding fresh air handling unit manufacturer X is extracted sequentially when the water supply temperature is a. i The maximum dehumidification capacity of the 4-row pipe equipment is Δd1, the maximum dehumidification capacity of the 6-row pipe equipment is Δd2, and the maximum dehumidification capacity of the 8-row pipe equipment is Δd3. Determine the theoretical dehumidification capacity Δd sequentially X With the fresh air unit manufacturer X i The relationship between the maximum dehumidification capacities Δd1, Δd2, and Δd3 of different devices: If the current water supply temperature is a, the theoretical dehumidification capacity Δd... X If the dehumidification capacity exceeds that of all devices, the water supply temperature a will be gradually reduced, and the judgment will be repeated at each temperature value. If no suitable equipment is available at the lowest water supply temperature, switch to the next fresh air handling unit manufacturer, X. i+1 Repeat the above process until the theoretical dehumidification capacity Δd can be met. X Maximum water supply temperature t g1 And determine the corresponding fresh air unit manufacturer X i and the corresponding equipment piping selection; If all equipment from all manufacturers cannot meet the requirements, then t g1 Set the temperature to 9℃ and select the device with the maximum number of pipes; S6, Fan coil unit dehumidification capacity assessment: First, set the initial parameters: the initial value of the fan coil unit manufacturer's serial number is j=1, and the corresponding initial value of the water supply temperature b is set to a range of 10. 15℃; Then, based on the equipment parameters provided by all n fan coil unit manufacturers, extract the maximum dehumidification capacity Δd4 of the 2-row equipment, the maximum dehumidification capacity Δd5 of the 3-row equipment, and the maximum dehumidification capacity Δd6 of the 4-row equipment of the corresponding fan coil unit manufacturer Pj when the water supply temperature is b. Determine the theoretical dehumidification capacity Δd sequentially P With the fan coil unit manufacturer P j The relationship between the maximum dehumidification capacities Δd4, Δd5, and Δd6 of different devices: Given the current water supply temperature b, the theoretical dehumidification capacity Δd... P If the dehumidification capacity exceeds that of all devices, the water supply temperature b will be gradually reduced, and the judgment will be repeated at each temperature value. If no equipment meets the requirements at the lowest water supply temperature, switch to the next fan coil unit manufacturer, P. j+1 Repeat the above process until the theoretical dehumidification capacity Δd can be met. P Maximum water supply temperature t g2 And determine the corresponding fan coil unit manufacturer P j and the corresponding equipment piping selection; If all equipment from all manufacturers cannot meet the requirements, then t g2 Set the temperature to 9℃ and select the device with the maximum number of pipes. S7. System water supply temperature is determined.

2. The design method for a centralized air conditioning system with medium-temperature chilled water according to claim 1, characterized in that, The initial data extraction and initial judgment in S1 specifically include the following steps: S11. Extract the calculated dry-bulb temperature and wet-bulb temperature of the outdoor air conditioner; extract the indoor design operating temperature and relative humidity. S12. Further determine the outdoor air humidity and indoor air humidity using the enthalpy-humidity chart; S13. Determine whether it is necessary to adjust the selection and design of conventional fresh air handling units and fan coil units.

3. The design method for a centralized air conditioning system with medium-temperature chilled water according to claim 2, characterized in that, S13 determines whether the selection and design of the conventional fresh air handling unit and fan coil unit need to be adjusted. Specifically, it is determined whether the outdoor air humidity is greater than the indoor air humidity. If the outdoor air humidity is not greater than the indoor air humidity, there is no need to adjust the selection and design of the conventional fresh air handling unit and fan coil unit. The water supply temperature is directly set to 15℃, and the terminal coil equipment is directly selected. Otherwise, continue to S2 to calculate the indoor heat-moisture ratio and determine the air supply state point.

4. The design method for a centralized air conditioning system with medium-temperature chilled water according to claim 1, characterized in that, The S3 calculation of the dehumidification capacity of the fresh air handling unit and fan coil unit specifically includes the following steps: S31. Calculate the dehumidification capacity of the fresh air handling unit; S32. Calculate the dehumidification capacity of the fan coil unit.

5. The design method for a centralized air conditioning system for medium-temperature chilled water according to claim 4, characterized in that, The step S31, which calculates the dehumidification capacity of the fresh air handling unit, includes the following steps: Calculate the theoretical dehumidification capacity ,in This refers to the moisture content of indoor air after dehumidification by the fresh air handling unit. Specifically, it's the moisture content at point L, determined by the isenthalpic or isohumidity curve of the indoor air after fresh air treatment. ;in It is the humidity content of outdoor air.

6. The design method for a centralized air conditioning system for medium-temperature chilled water according to claim 4, characterized in that, The S32 calculation of the fan coil unit's dehumidification capacity includes the following steps: Calculate the enthalpy h at the fan coil unit outlet based on the total air volume and the fresh air volume. M Connect L and O and extend with enthalpy h M The intersection points are determined, and the intersection point M is obtained. The moisture content at point M is then calculated. Therefore, the dehumidification capacity of the fan coil unit can be calculated as follows: ;in It refers to the indoor air humidity.

7. The design method for a centralized air conditioning system for medium-temperature chilled water according to claim 1, characterized in that, The determination of the water supply temperature of the S7 system specifically includes the following steps: Based on the highest water supply temperature t obtained from the dehumidification capacity assessment of the S5 fresh air handling unit. g1 And the highest supply water temperature t obtained from the dehumidification capacity assessment of the S6 fan coil unit. g2 Determine the magnitudes of the two values, and take the lower water supply temperature as the system's water supply temperature t. g .

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