Weak current College】 【air-conditioning system design principles.

<br> 1, air conditioning water system design principles <br> Conditioning system design should adhere to the principles of design are: <br> L * to the hydraulic balance; <br> L * prevent large flow small temperature difference; <br .> L * water transfer coefficients in order to comply with regulatory requirements; <br> L * variable flow system should be frequency regulation; <br> L * to handle the water system expansion and exhaust; <br> L * to solve water treatment .and water filtration; <br> L it is necessary to pay attention to net cooling effect with warmth. <br> ⑴, water system design should aim at the loop of the hydraulic balance <br> L a, technical requirements <br> L .air cooling, heating and water system, should be consistent with each loop between the hydraulic balance requirements. On the pressure differential vastly high resistance loop, you should set the secondary circulation pump. The loop should set balance valve or split-tee, balancing device .. If the pipe shaft area allows, you should try to use pipe vertical with the program. <br> (2) to prevent large flow small temperature difference <br> L a, causing large flow of small temperature difference <br> L ★ .design flow is based on the maximum design cooling load (or heat) and then by 5 ° c (or 10 ° c) temperature determine the backwater, and the fact that appear most design cooling load (or thermal load), that is, the .full-load operation time is only a short period of time, most of the time it is run under partial load. <br> L * pump lift is generally based on the most distant loop, maximum resistance and multiplied by a factor of safety is .identified, and then a combination of the design flow, find its consistent pump nameplate parameters and determine the water pump model, instead of depending on pump performance curve determine the pump model. Therefore, the actual pump, water pump working point is in the lower .-right corner of the nameplate working point, so the actual flow side than design flow 20% -50%. <br> L * in larger water system design, the design calculation is often not conducted for each loop, the hydraulic balance check for .pressure differential vastly loop, most are not set balance valve balancing appliances, construction after installation without any debugging, loop resistance unbalance between the hydraulic and thermal cycle disorders like now had to * large flow to cover it. <br> l <br> La ., avoid large flow of small temperature difference <br> L * considering design time difficult the loop hydraulic balance between strict, as well as the construction and installation of various uncertain factors, in each loop should set balance valve balancing devices, such as to ensure .that in actual operation, the loop to achieve better between the hydraulic balance. <br> L when one or several branch loop than other loop pressure differential vastly (such as resistance poor 100kPa above), it should be in the loop creation of secondary circulation .pump. <br> ⑶, water system expansion, make-up water, drain and vent <br> L a, water system expansion <br> Closed air conditioning frozen water system, the highest point above the water line 1-2m Office expansion .tank. Expansion tank General optional standard tanks (T905 (1), its volume range 0.2-4.0m3. expansion tanks equipped with expansion pipe, make-up water pipes, water pipes and the overflow drain piping, and should have a water level control .instrument or ball. <br> La, water system of water supply and drainage <br> L water system of water and water should be achieved through the expansion tank. Therefore, you should separate the expansion pipe and cooling station return water mains (or .water) touch, so that the system installation and commissioning of new water or in the usual operation of water, through expansion tank water injection. The whole water system water from lower water mains (or water) from low to high, which will air in .the pipeline system from the bottom up through the exhaust valve and expansion tanks. Many engineering installation for corners, the expansion of the expansion tank and a higher point nearest the return pipe touch, leaving the system air is difficult to exclude water pressure incurred is not .stable for a long time. <br> L water system of drainage valve should be set at the lowest point of the system (water or refrigerator water pipeline lowest point) so that when the pipeline system in the Shui all excluded. <br> La ., water system of exhaust <br> L installed on each floor of the building's air blower plate Tube, air supply unit has reached the highest point at the end of the return pipe shall be fitted with automatic discharge valve. As long as the loop branch .so that the pipe bends more certain, or pipes to avoid fire hose, air supply pipe and fittings in the ceiling of a large cross section cable and so on and upper and lower corners, should be the highest point in turning set automatic discharge valve. .Hotel water system common cons and is water with gas, and gas and it is difficult to exclude, the reason is the automatic valve is set too low or set incorrectly. <br> ⑷, water system of water treatment and water filtration <br> .L civil buildings air conditioning water system of water treatment, has not yet given rise to some designers. Long loop using chilled water and cooling water often bicarbonate, bacteria and algae and debris, and other factors, make the chiller in the evaporator and condenser, .heat exchange device scaling or corrosion, thereby increasing the equipment thermal resistance, reduce cooling capacity and unit life. <br> Water treatment: effect of better water treatment with drugs and electronic water treatment method. Pharmaceutical water treatment used for cooling water system of water .treatment, there is a general-purpose, with corrosion and scale. The electronic water treatment is not only applicable to cooling water system, but can also be used for the chilled water (cold water) system of water treatment, different specifications of electronic water .treatment can be installed in the caliber DN12-DN300 pipeline, water treatment effect was very clear that at present in a number of projects have been widely used. <br> Water filtration: in the Shui system setting water filter to filter out circulating water dust .fibers, sand bricks, vegetal Flammables, etc. Commonly used filter has a metal mesh and nylon mesh filter, y-pipe filters, etc. In the Shui system operation during filter to settle on a regular basis to ensure the smooth flow of water. .<br> ⑸, tubeNetwork for cold insulation and thermal insulation <br> L refrigeration and air conditioning supply often cold insulation (insulation) material and thickness design or construction, the resulting amount of cold (hot), and in summer the loss may produce .large amounts of condensation water and the impact on the environment. <br> LA, air-conditioning for the cold water pipe cold insulation thickness of economic <br> L cold water pipe in the thickness of the cooling economy according to GB GB50189-93 ., should not be smaller than the data in the table below. <br> Thermal insulation thickness selection reference tables <br> Cold water pipe (or hot water pipe) of nominal diameter <br> Dg [mm] ≤ 3240 ~ 5580 ~ 150200 .~ 300> 300 <br> Thermal insulation thickness <br> Polystyrene (self-extinguishing) 40-4545-5055-6060-6570 <br> Glass wool 3540455050 <br> 2, water system thermal stability issues (to be perfect) < .br> 3, condensation water system design (perfecting) <br> Choice of 4, water pump <br> Select pump based on flow and pressure head L (or head) P as follows: <br> L-in-design of maximum .flow [m3 / h] <br> L 1.1 or 1.2 - additional factor, when the pump when a single work; two of 1.1 in parallel work of 1.2. <br> L-in-pipe network most adverse loop total resistance calculation value .[kPa]; <br> L 1.1 ~ 1.2 - additional coefficient. <br> L General resistance for heating: pipeline is 80 ~ 200Pa / m, main road, resistance to 60kPa, considering the end fittings, valve, strainer, heat exchangers .and other local resistance, the total resistance of about 190 ~ 30kPa. <br> L General for air conditioning: the farthest loop length and 60 ~ 200m, General press 200 ~ 500Pa / m ratio friction determine pipe diameter, total resistance around $ 100 .~ 350kPa <br> 6. noise control measures <br> 1. air conditioning system noise reduction should take the following measures <br> L (1) main consider reducing noise from sound sources, selection of air conditioning devices should use small vibration, .low noise, such as low noise compressor, motor, fan, pump, air conditioner, fan-coil, etc. <br> L when the air conditioning system of the air flow must, choose fan pressure head safety factor should not be too big .and, if necessary, the selection of the blower and the burden back to fan the common system of total resistance. <br> L (2) in the design of the air conditioning duct system duct should minimize resistance, pipeline of local resistance is not .too large, minimize the rheostat pipe, elbows, three road, air valve and so on. Each air supply system of total air volume and resistance should not be too big and, if necessary, the large air flow system is divided into several small wind .systems. <br> L (3) minimize the air temperature to reduce air, air flow is reduced, fans may also be appropriate to reduce the number, the noise reduction. <br> L (4) air duct in wind speed should, .as far as possible, that it may reasonably be required to reduce wind noise reduction, fade. <br> L (5) in the refrigeration and air-conditioning equipment and security measures to reduce noise. <br> L (6) in the .wind pipe and muffler elbow of additional facilities, such as muffler, muffler elbow. <br> L (7) in the room or air conditioners to increase noise absorbing materials, noise. <br> L8) according to the duct outlet air flow and .flow rate to determine the effective flow muffler section. (Through the Interior of the wind speed is not greater than the muffler 5m / s, muffler elbow of the wind speed is not greater than 8m / s through other types of wind speed is not greater .than the muffler 10m / s). <br> <br> <br>.