【 Weak current College 】 Central air conditioner selection guide (2)

Standard chiller for quantity of heat is the cooling capacity of 80 per cent, that is, if the heat load (such as refrigeration for sanitary hot water, or heating time for hot water or space heating load greater than cooling load), you can choose the high-voltage generator with large capacity, in order to improve the heating or select large cooling capacity unit to achieve (such a large initial investment). Each step of a number of high-voltage generator, heating capacity increased by 20 per cent increase, Q = 0.8 × 0.2. If summer cooling and hot water supply (by summer cooling capacity selection) are: or, and n is the increasing number of high-voltage generator. If the system needs summer refrigeration, winter heating and sanitary hot water supply (fulfill summer cooling capacity requirements checking after the selected models for quantity of heat in winter):

① meet summer and winter seasons usage requirements;

② as heat load in winter, take greater high-voltage generator meets;

③ If heat load in winter, take increasing unit model to meet the requirements (that means a unit increase the cooling capacity models). If you need to increase the unit model meets the requirements, the summer by regulating the burner to keep the economy running. In the transitional seasons system they rely on regulating the burner head to ensure economical operation. In addition, the cooling capacity and the proportion of the quantity of heat can also be used to adjust the implementation of some of the valve.

(6) heat pump unit

★ Unit load selection of air-source heat pump unit is normally based on building the capacity of the choice of the summer cooling load, thermal load in winter to check calculation. If the amount is greater than the unit heating heating load, then the units meet the requirements of winter heating; if the heating load is greater than the unit quantity of heat, you can press the following 2 situation considerations: when a unitquantity of heat heating load of less than or equal to 50% and 60%, you can increase the auxiliary electric heating appliances; whereas it should be considered at the beginning of the investment and operating costs to determine the unit of capacity, that is, the installed capacity of the appropriate increased unit.

¡Ï auxiliary electric heating installed capacity of air-cooled heat pump air conditioning system with auxiliary electric heating devices have the following forms are available: (1) in the fan coil system set small boiler to improve the water temperature in winter unit; (2) in other sources of heat (hot water or waste water), use the pull-type heat exchanger increase winter water temperature; (3) direct burn (air supply for water, gas, diesel day) to improve the water supply temperature of the heater in winter; (4) with electric heater for improving the water supply temperature in winter.

★ Cool (hot) load in select air source heat pump unit, you should also consider building cool (hot) load. General public buildings, air conditioning equipment are often intermittent operation, that is run during the day, night off, so the day running, since the building's thermal (heat), room temperature needs to run after a certain amount of time to achieve the set value, if shorter this time, the choice of unit, we should consider the accumulation of cold (hot) load. It and cooling (heat) time-related, General cooling (heat) times 2 ~ 3h.

(VII) summarization of combined air conditioner class

At present, the comprehensive functionality of high-rise building of the central air-conditioning system, often to the desired temperature, humidity, ventilation rate, cold (heat) load of air distribution, uses a tiered or partition for centralized processing, its advantages are ease of building property management and use of energy.

Combined air conditioner is a combination of cell function, the user may act according to the air conditioning andair treatment needs, choose the desired sections for free permutations and combinations, have great freedom and flexibility.

Considering the operation and maintenance convenience, air evenly and other factors, should be appropriately set up middle segment.

Selection must note the following points:

1, the manufacturer provides a combined air-conditioning unit features a combination of a paragraph. Map to be given on the selected unit model, specification, section number, feature length, arranged in the order and left-position, and other basic requirements.

2. combined air-conditioning unit operation surface provides for:

(1), back to the fans have one side of the transmission belt;

(2) bag filters capable of handling filter bag side;

(3) automatic winding type filter is equipped with one side of the control box;

(4) cold (hot) media import and export side, the drain side;

(5) washers (above) of water sprinkler fittings.

When people in the face of the unit operations, air blow to the right, on the other hand to right-to-left-style, selection and ordering instructions required for left and right.

3. Select the table coolers, heaters and muffler, you must set the filter (below), to protect the heat exchanger and muffler surface cleanliness to prevent plugging holes, sewing, and should be set in the middle segment.

4, paragraphs, tables, cold water, and so on, apart from the existing sewer received to the air conditioning unit, you should consider the drainage of water plant.

5. choose washer (above), you should note a few level rows.

6. Select the table coolers, heaters (above), should indicate the type and number of rows, use the cold (hot) media properties, such as temperature and pressure. Unit with steam heating, air temperature not less than 20 ° c; to hot water heating, air temperature not less than 15 degrees centigrade.

7. choose dry steam humidifier requiresinstructions humidification, for steam pressure and controls methods (manual, electric or pneumatic).

8. choose the fan section to illustrate fan models, specifications, installation forms, outlet locations, the fan should be set before the middle segment, ensuring uniform airflow. Air supply unit air enthalpy drop should be not less than 34kJ/kg.

9, indicate the location of the air interface, orientation and size, delivery, return air valve type, specifications, the use of control mode (manual, electric or pneumatic). Blower outlet should have flexible short-tube, windMachine base should be damper.

10, needs to stay out of the hole and instrument mounting hole locations and the locations of fan power supply lead.

11, unit basis shall take precedence over the Interior of the plane, there should be based around the floor drain, drainage ditch or to exclude the condensation water and the water at the bottom of the venting device.

12, unit around or unit and unit (multiple) layout should be sufficient for the operation and maintenance of space.

13, taking into account the anticorrosion performance unit, Cabinet material best selection of galvanized steel, glass steel or special alloys. For ferrous metals production component surface should be made for anti-corrosion treatment; should be used in fiberglass body oxygen index of not less than 30 of flame retardant resin production.

14, unit standard air leakage rate:

(1) unit within the static pressure to maintain 700Pa, unit air leakage rate is not more than 3%

(2) clean air conditioning system of units within the static pressure to maintain cleanliness 1000Pa, less than 1000 level, unit air leakage rate is not more than 2%; cleanliness level is greater than or equal to 1000, the unit is not greater than the air leakage rate of 1%.

On unit performance appraisal requirements: unit of the air flow, pressure, cooling and heating of the measured value should be greater than or equal to the nominal value of 93% water resistance unit-and the input power of the measured values must not be greater than the nominal value of 110%.

Basic parameter should satisfy the following requirements:

A unit volume measured value not less than 95% of the rated value, full pressure measured value not less than the rated value of 88%.

B unit rated cooling capacity of air enthalpy drop should be not less than 17kJ/kg; air supply unit air enthalpy drop should be not less than 34kJ/kg.

C the amount of air turbine heating temperature at least should not be less than steam heating temperature 20 ° c hot water when heated temperature 15 ° c

Unit in 85% of rated voltage start properly and working.

Unit of the coil and the pipeline in any or all of the following conditions should be long-running, and no leakage:

A cooling coil in 980kPa pressure, or pass hot water used in 980kPa pressure, 60 ℃ hot conditions;

B hot water coil in 980kPa pressure, 130 ° c under the conditions of hot water;

C steam coil in 70kPa pressure, 112 ° c for steam conditions.

Unit inside the insulation, acoustic materials with non-toxic, no smell, self-extinguishing and non-absorbent performance. You should not use bare asbestos or fiberglass material. Insulation, acoustic materials and panels should be strong, smooth, seamless, out-of-the box at run time without condensation on the surface.

Condensate water treatment unit should be set, outside of the box in the run should not be leaking water, there should not be stagnant water in the tank, drainage should be smooth.

Box and check the door should have good air tightness, air leakage rate of less than 5% be-check locking performance is much better to prevent internal and external pressure differential switch itself. Coil face the wind, the wind speed exceeds 2.5m/s should be retrofitted retaining plate. Water jet segment into, out of thewind side should have excellent water board.

Unit box should have adequate stiffness, running should not be deformation. Units using ferrous material, the surface should be treated with preservatives.

Summary of chapter III of the auxiliary equipment selection

First, the water pump class product selection guide:

1. Select clear water pump mainly see parameter flow and head;

2 centrifugal pump is suitable for large-volume, large-head of the establishment;

3, pipeline pump flow range is not large, applies to lift low places.

4. regular select horizontal pump, when the installation has limitations when selected vertical pump;

5. when the single-stage pump does not meet the requirements for select double-stage pumps;

6. when the temperature of 65 ° c, t > hot water pump is selected; when t ≤ 65 ° c, cold water pump.

Second, the new fan equipment selection steps are as follows:

1, according to the installation settings to select new fan;

2. the device air flow, pressure when you choose to not less than the design value is in principle;

For special industries, such as hospital (operating room, intensive care Wo Ward), laboratory, workshop, according to the instruments industry related regulations identify needed new air flow.

3. determine the amount of refrigeration and heating design operating conditions;

4. in principle, a fresh air handling units only a floor of new air volume required;

Third, fan-coil equipment selection steps are as follows:

1. clear the selection of unit type, specifications, diffusers, and so on.

In the selection of fan coil unit refrigeration units, is to design warm-up load and thermal load unit display. In most cases, coil have sufficient latent heat capacity, can meet the design requirements. If using outdoor air is appropriate dressing their load and calculation formula: water temperature rise (° c) = air temperaturerise (° c, db)

First to determine the work requirements:

Refrigeration: indoor warming refrigeration load (), the total heat indoor cooling load (), the air temperature (° c, db/℃ wb), the water temperature (° c), the amount of wind ();

Heating: usually chosen by the refrigeration unit, heating capacity is adequate, receipt of same by water flow to selected. That is, with water temperature for indoor heating load required. Indoor heating load (), the air temperature (° c).

Then determine the unit specifications, quantity, temperature and requiredPressure drop, and other parameters.

2, clear the selection of the unit of water left out or closing out a direction (and related piping layout etc).

3. clear fan motor bearings is used for oily or not oily axis pump. If you choose not to use the oil axis pump, consistently within regular refueling.

4, notice the water of the thermal insulation measures so as to avoid the summer use of condensation, defaced indoor building.

5, hot water, water temperature in winter pass normally does not exceed 60 ° c, could reduce scaling of alternating hot and cold while mitigating role expanding lhe forces weakened, affecting heat transfer.

6, unit coil set the highest operable.

IV. Summary of cold water tower

1, according to the cooling water temperature: temperature in high-temperature Tower, Tower, Tower.

2. follow the installation location of the current situation and the requirements for noise: crossflow Tower and countercurrent Tower.

3. follow the chiller cooling water cooling water selection, in principle, slightly larger than the cooling tower water chiller for cooling water.

4. selection of multiple water tower to select the same model.

Secondly, the cooling tower selection need attention:

1, Tower body structure material to stability, durability, corrosion resistance, assembled with precision.

2, water allocation uniformity and Wall flow less splattering device selection is reasonable, is not easy to stop up.

3. spray fillers of the type conforms to the requirements for water quality, water temperature.

Match 4, fan, to guarantee long-term uptime, no abnormal noise and vibration, and leaves with good resistance to water erosion and is of sufficient strength. Fan blade installation angle adjustable angle to ensure consistent and motor current not exceeding the rated current of the motor.

5. low power consumption, low cost, small and medium-sized steel framed glass Tower also calls for the quality of light.

6, Tower should try to avoid the heat source, exhaust and flue gas occurs at the point, chemicals and coal pile piled nearby.

7, cooling tower or tower and the distance between other buildings, apart from considering the requirements of ventilation Tower, Tower and building mutual influence, you should consider building fire, explosion-proof safety distance and the construction and maintenance of cooling towers.

8, cooling tower of fles direction by 90 °, 180 °, 270 ° rotation.

9, cooling tower of the material is resistant to low temperatures-50 ° c, but the average temperature for the coldest month is less than-10 ° c in the region should indicate when ordering in order to take measures to prevent icing. Increase in the cost of cooling tower is about 3%.

10, the cycle of water turbidity is not greater than 50mg/l, short-term 100mg/l is not greater than not contain oil and mechanical impurities, if necessary, take out the algae and water stabilization measures.

11. water distribution system is designed for nominal amount, such as the actual difference between the water and the nominal quantity of ± 15%, when ordering should indicate to modify the design.

12, cooling tower parts in storage during transport, it shall not be pressing weights, and attention to fire exposure. Cooling tower and installation, transportation, repair process must not use electricity, gas welding, flame, no use of firecrackers in the vicinity of the fireworks.

More than 13, round tower, Tower and Tower design between net distance should remain less than 0.5 times Tower body diameter. Countercurrent flow cooling tower and the square Tower can be side-by-side layout.

14, selection of the pump should be equipped to ensure the flow of cooling tower, lift and process requirements.

15, when you select multiple cooling towers, use the same model as possible.

In addition, measure the effectiveness of the cooling tower is usually also adopts three indicators:

(1) cooling tower water inlet temperature and outlet temperature t1 t2 difference Δ Δ t t, is known as the cooling water temperature, in General, the higher the temperature, the cooling effect is better. In terms of production, the greater the Δ t production equipment cooling water flow rate can be reduced. But if the water temperature t1 is high, even if the temperature difference between Δ t, cooling water temperature may not be reduced to meet the requirements, so this indicator is needed, but the description of the problem is not comprehensive enough.

(2) cooling water temperature t2 and air wet-bulb temperature ξ proximity Δ Δ t ', t ' = t2-ξ (° c), Δ t ' called cooling high. Δ t ' value is smaller, the better the cooling effect. In fact Δ t ' could not be equal to zero.

(3) into account in the calculation of the cooling towers of tricking water density. Tricking water density refers to the effective area of 1m2 every hour on the cooling water. Q with symbols. Q = Q/F, m3/m2.h (Q-cooling flow, m3/h; effective F-cooling tower water spray area, m2)

Other notes:

1. in accordance with the conditions and amount of water to determine its main parameters.

2. optimization for efficient (the same water body machine small).

3. optimization of low noise (the same water faninput power low noise low).

4. packing material good long life, flame-resistant packing optimization for first.

5. selection location consideration should be given effect by the monsoon.

Requirements:

1, the resistance of pipe cannot be lower than fill pipe inlet diameter.

2, cooling tower water pipe valve closer from the Tower, the better.

3. recommends that the return pipe insulation outdoor part.

4, multiple parallel cooling recommendations made two road, waterway, easy to adjust in units of energy-saving operation.

5, cooling tower startup must first openAfter the water pump, blower. Not allowed in the absence of rain water is fan operation.

Therefore, in the water pipe is equipped with a tilt of the water board, if you start the fan without water, the water distributor flip, water boards will scrape to packing, packing away by the wind blowing out or cloth water card bad, cooling tower starts, we must first open water pump, blower, open back stopped working, first stop after stop water pump, blower.

5. air inlet product selection guide

1. first, according to technological requirements and field conditions, etc., determine the form and sent back to the wind, air distribution and air outlet type;

2. Secondly, according to the air flow to determine the dimension of the diffusers;

3. once again, the selection is also note the following requirements:

(1) General use louver or slit air outlets, and other side sent, conditional, should be affixed to the side to send air flow. Process air conditioning room, when the room temperature permitted fluctuation range is less than or equal to ± 0.5 ℃, the air should stick to the side to send.

(2) when there is a ceiling available, according to the room height as well as the use of the site on the air, using circular, square and gap type diffuser and orifice plate air. When the unit area air is big, and workspace called wind smaller or regional temperature requirements strictly, should adopt the orifice plate air.

(3) space for a large public building and room temperature permitted fluctuation range is greater than or equal to ± 1.0 ¡æ tall plant, use vents or swirl diffuser air.

Used to attach the side sent, should meet the following requirements:

(1) air distance from the ceiling on the edge of the large, air services should be set up 10-20 degrees centigrade of diversion.

(2) air should be set so that the Jet is not about skewed to the Distributor.

(3) there shall be no Jet process stops. In addition, air export wind speed, air distribution, air type, installation height, Interior allows wind speed and noise standards, and other factors. Muffler requirement is high, the use of 2-5m/s, vent air can take 4-10m/s.

Back to the arrangement of diffusers, should meet the following requirements:

(1) back on the air outlet should not be located in the Jet area and who stay for a long time, the use of the site, the side to send in the air of yishe with side.

(2) where applicable, may be set back to the wind or corridor air return, but Corridor section wind speed should not be too large.