It is recommended not to exceed 100% when starting up at the same time or high utilization rate at the same time; It is recommended that the maximum value should not exceed 130% when the machine is not started at the same time or the simultaneous utilization rate is low.
The circulating air volume is the room volume multiplied by the ventilation rate.
The elevation of fan coil shall be consistent as far as possible, and the height of embedded fan coil shall not be higher than 3m to ensure the air conditioning effect.
For comfort air conditioning, the ventilation rate should be 5-8 times per hour.
E.
Indoor and outdoor unit ratio refers to the ratio of the sum of indoor mechanism cooling capacity and the sum of outdoor mechanism cooling capacity converted into percentage value.
Generally, when the one-way distance exceeds 40m, the same process pipe layout shall be considered, as shown in the following figure: Contrary to the disadvantages of different programs, the advantage of the same program is that the length of water pipeline is basically the same regardless of the distance between each end and the main engine.
6.
Precautions for the design of the air conditioning water system: A.
The sum of water pressure drop and pressure drop along the way of various pipe fittings in the loop.
For other ventilation times, please refer to the following table: chilled water system design: 1.
2.
The model of terminal equipment shall be selected according to the area, function and load of each room.
The head of the pump shall be 1.1 ~ 1.2 times of the total water pressure drop of the most unfavorable loop of the water supply and return pipe network.
Hmax= Δ p1＋ Δ Where P2 + 0.05l (1 + k): K is the ratio of the sum of local resistance equivalent length in the most unfavorable loop to the total length of straight pipe..
When the pressure at the inlet end of the chiller is greater than the pressure bearing capacity of the chiller, but the system hydrostatic pressure (including the height of the underground building where the chiller is located) is less than the pressure bearing capacity of the chiller, the cold water circulating pump can be installed at the outlet end of the chiller, and the water system can not be divided vertically.
The maximum installation height and minimum installation height shall be calculated respectively according to different types of fan coil.
F.
Places with strict requirements on noise value should not be installed in the room.
D.
The load shall consider the orientation of the room, the heat dissipation of equipment in the room, the thermal insulation degree of enclosure structure, etc.
Selection of chilled water pump: centrifugal clean water pump with rotating speed of 30 ~ 150 revolutions per second is usually selected, and the flow of water pump shall be 1.1 ~ 1.2 times of the rated flow of chiller (1.1 for single operation and 1.2 for two or more parallel operation).
3.
First understand whether the air conditioning system has fresh air requirements, and calculate the maximum fresh air volume and minimum fresh air volume when there are fresh air requirements.
When determining the pressure of the air conditioning water system, the system pressure must not be greater than the pressure bearing capacity of the chiller, end equipment, water pump and pipeline components.
Generally, the building height is less than 100m, and no division can be made; If the building height exceeds 100m, zoning is generally considered vertically.
When there are a large number of end equipment in the pipeline and the distance between each end equipment and the main engine is large, the same program pipeline shall be applied.
The total water pressure drop of the most unfavorable loop, including the water pressure drop of the chiller evaporator Δ P1.
Configure the flow of the water pump according to the flow of the end equipment, calculate the resistance along the way of the water system, determine the head of the water pump, and then select the model of the water pump.
In the air conditioning system, the pipe diameters of all water pipes are generally calculated according to the following formula: recommended water velocity in the pipe: 4.
B.
The connection between the equipment and the air duct shall adopt soft connection to prevent vibration and noise from being transmitted to the air duct.
2.
When the equipment floor is set in the middle floor, air-cooled units should be preferred, and the floor height should meet the design requirements.
Select and design the host equipment according to the load of each room.
An access hole shall be reserved at one side of the connecting pipe of the fan coil to facilitate maintenance, and the size of the access hole (not less than 400) shall be considered × 400), whether there is flammable and corrosive gas leakage, oil mist, etc.
Basic conditions and requirements of design: 1.
when the cold source equipment is arranged on the floor, the vibration isolation and noise transmission of the equipment must be fully considered and properly solved.
Otherwise, due to the high wind speed at the air outlet, great wind noise will be generated.
2.
The basic information includes the location of the machine room, energy, use of air conditioning, etc.
The production plant shall compensate the exhaust air, maintain the indoor positive pressure or ensure the maximum fresh air volume of no less than 30m3 / h per person.
Design parameters of air conditioning host: design parameters of air conditioning terminal: system design requirements: 1.
When designing the air handling unit, the noise of the air-conditioning room shall be considered.
Fresh air volume design: 1.
When the cold water circulating pump is installed at the outlet end of the chiller and the constant pressure point is located at the inlet end of the chiller, if the resistance of the chiller is large and the height of the building and expansion tank is low, the suction inlet of the pump may produce negative pressure.
in the room.
When the hydrostatic pressure of the water system is greater than the pressure bearing capacity of the standard chiller, the reinforced chiller with higher working pressure shall be selected, or the water system shall be divided vertically: the vertical division of the water system shall depend on the building height.
Scheme comparison: determine the most economical and applicable scheme according to the basic situation of the project.
The water pressure loss of each air conditioning terminal device in parallel in the loop is the largest, and the water pressure drop of the other one Δ P2.
The water pressure drop of the evaporator of the chiller and the end device of the air conditioner can be found from the product samples according to the design conditions; The local loss of loop pipe fittings and the loss along the loop shall be calculated by hydraulic calculation.
Exceeding this value will seriously affect the air conditioning effect.
There should be a description of the scheme, including project overview, design parameters, host installation location, cooling tower installation location, air conditioning mode, etc.
C.
shall meet the specification requirements and the actual situation of the project, the configuration of fresh air volume, the design length of air duct, wind speed, static pressure, the installation height of outdoor unit, noise, air distribution form, etc.
Location of outdoor host: 2.1 the installation location of outdoor host shall have smooth air, good heat dissipation and no short circuit; In case of poor heat dissipation, improvement measures shall be considered, such as adding air duct, grille, etc; 2.2 the noise of the unit will not affect the surroundings; 2.3 multiple external units shall be arranged neatly and beautifully, the distance between peers shall be more than 200mm, more than 1m maintenance space shall be reserved between the two rows, the air outlet and return of each unit shall not affect each other, the elevation shall be consistent as far as possible, and the height difference shall be less than 0.5m; 2.4 A 10mm thick damping rubber plate shall be added between the unit and the foundation; 2.5 whether there is enough maintenance space around the main engine, whether there is radiation source, whether there is corrosive gas, whether it is a flammable and explosive environment with much oil fume, and whether it is conducive to the discharge of defrosting water.
3.
The fresh air volume of the building shall be adopted according to the use nature of the room in the following table: 2.
First, understand the project overview, room function, room area, whether each room needs air conditioning, and the owner’s basic requirements and intention for air conditioning, so as to make scheme comparison and design.
When there are few end equipment in the pipeline and there is little difference between each end equipment and the host, different program pipeline can be used, as shown in the following figure: this form has the advantages of simple pipeline and convenient installation, but the hydraulic loss of each coil is different due to different distance from the host, resulting in hydraulic imbalance of each coil, This leads to a deviation in the distribution of cold (heat) quantity.
The following aspects shall be considered in the design: the room load configuration, the ratio of internal and external units, the equipment installation location, water pump, cooling tower, etc.
the sum of the length of supply and return pipes) is l, the head H (mh2o) of the cold water pump can be estimated according to the following formula.
Generally, the cold water circulating pump should be installed at the inlet end of the chiller.
The disadvantage of the same program is that the pipeline is more complex, which brings inconvenience to installation and construction, and the cost is higher than that of the water circulation of different programs.
In addition, an air duct must be added to directly blow the air indoors.
3.
For the location of end equipment, when designing the fan coil unit, it shall take into account that the air flow in the room is well organized, evenly distributed and the spacing between return air outlets is moderate.
The fresh air volume is considered as 10-15% of the circulating air volume.
The wall thickness of the water pipe shall meet the following standards: 5.
Indoor and outdoor unit ratio.
In this way, if the total length of the most unfavorable loop (i.e.
H.
This overcomes the disadvantage of hydraulic imbalance.
During estimation, the loss along the loop per 100m pipe length can be roughly taken as 5mh2o.
4.
A silencing static pressure box shall be added at the air supply outlet of the air-conditioning box to reduce the fan noise and uniform air supply.
2.
