الفرق بين تشيللر التبريدى بالمياه والتبريدى بالهواء

Air Cooled Vs. Water Cooled Chillers

مجموعة تكنولاب البهاء جروب

عميد دكتور

بهاء بدر الدين محمود

استشارى معالجة المياه

01117156569

The difference is big.

With a water cooled chiller, there is a unit located in the building that acts as the driving force to transfer the heat from the building water loop to a secondary loop (condenser water loop).

The second water loop is then run up to a cooling tower usually located on the roof of a building where the heat is then expelled to the atmosphere. High efficency with these type of devices.

With an air cooled chiller, there is no secondary water loop, and the primary water loop from the building runs directly up to the roof.

There, the chiller uses the thermodynamic principles of refrigerants to directly remove the heat to the atmosphere.

There is less equipment with this system, but the efficiency is half that of the water cooled systems.

Also, air cooled chillers are limited in the total size of the cooling system that they can adaquatly handle, where as water cooled chillers can be much much larger.

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What is difference between air cooled & water cooled engine?

Air cooling uses airflow directed at fins on the cylinders and heads is the cooling medium:

heat is transferred directly to the air.

The air comes either by natural convection (e.g., a motorcycle) or by forced air (e.g., air-cooled VW or Porsche engine.)

Water cooled engines circulate coolant around the heads + cylinders though a surrounding water jacket, and use a separate high-efficiency radiator for the final heat exchange to the air.

(Marine engines are a bit different - they use the surrounding water instead, either directly or though a water-to-water heat exchanger.)

Air-cooled engines are simpler, lighter and easier to maintain as they don't have the 'wet' cooling system elements.

They excel in cold climates where coolant freezing can be a problem. However, air cooling is less efficient due to the low heat capacity of air so these engines suffer from hot spots which reduces power, increases emissions and shortens their life.

Air-cooled engines are also considerably noisier - both from the engine directly and also from the air blower cooling fan if used.

Water-cooled engines take advantage of water's high heat capacity to efficiently carry away the heat.

So they offer the best control over temperature allowing for more aggressive / efficient tuning and optimal head design. While they have increased near-term maintenance costs (coolant, water pump, hoses, etc.) they make up for it in a longer-lived engine core (longer time between overhaul.)

Water-cooled engines are also quieter due to the insulating properties of the water jacket and the lessened airflow requirement.

Water cooling also permits more flexibility in engine architecture and installation since there isn't a need to duct cooling air directly to the cylinders.

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What is the difference between an air conditioner and a chiller?

AC is ----- which can convert air to hot as well as cold or we can say which maintains the temp. i.e. if it is hot it can cool the room n if it is cold outside u can warm the room.

A Chiller is a machine that produces chilled water (usually mixed with ~20% glycol and corrosion inhibitors) which is used to cool and dehumidify air in commercial and industrial facilities .t]

Use in air conditioning

In air conditioning systems, chilled water is distributed to air handling units as a refrigerant. These air handling units provide air conditioning to the building by running the incomming warm air through the coil of chilled water, transferring the heat from the air to the chilled water, thus, cooling the air.

A typical chiller for air conditioning applications is rated between 15 to 1000 tons (180,000 to 12,000,000 BTU/h or 53 to 3,500 kW) in cooling power.

Use in industry

In their industrial application, cooled refrigerant from the chiller is pumped through process or laboratory equipment.

Industrial chillers are used for controlled cooling of products, mechanisms and factory machinery in a wide range of industries.

They are often used in injection and blow molding, metal working cutting oils, welding equipment, die-casting and machine tooling, chemical processing, pharmaceutical formulation, food and beverage processing, vacuum systems, X-ray diffraction, power supplies and power generation stations, analytical equipment, semiconductors, compressed air and gas cooling.

They are also used to cool high-heat specialized items such as MRI machines and lasers.

Technology

There are basically four different types of chillers: Reciprocating, centrifugal, or screw-driven chillers are mechanical machines that can be powered by electric motors, steam, or gas turbines.

Absorption chillers are powered by a heat source (such as steam or hot water).

They have very low electrical power requirements - very rarely above 15 kW combined consumption for both the solution pump and the refrigerant pump.

Chillers can be air-cooled or water-cooled. Water-cooled chillers incorporate the use of cooling towers which improve heat rejection more efficiently at the condenser than air-cooled chillers.

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Water Cooled Chiller vs Air Cooled Chiller in HVAC System

Initial cost of air cooled chillers is lower than water cooled chillers as air cooled systems don’t require cooling towers,condenser water pumps and associated HVAC components.

Small systems are almost always air-cooled since the extra requirements of water treatment and maintenance are capital intensive and will not be offset quickly by the lower operating costs.

Larger HVAC water chillers are almost always water cooled

.HVAC engineers and technicians feel easy with maintenance free or less maintenance equipment.

Water cooled chillers may be preferred because of better heat transfer properties of water as compared to air cooled chillers.The primary advantage of water is that the film coefficient is 10-100 times better with water than air.

Film coefficient controls heat transfer with given constant area and temperature difference.

Water-cooled HVAC units make less noise and give more cooling per square foot.

While air cooled chillers have comparatively less cooling per square foot and are more noisy HVAC machines.

Noisy machines are annoying especially for occupants of nearest offices or zones.

While comparing air and water cooled chillers, an overall system cost (both running and installed) has to be worked out.

Size of HVAC unit matters when selecting the water cooled chiller or air cooled chiller.

Smaller HVAC units are usually air cooled, larger are water cooled.

HVAC engineers have to evaluate air cooled and water cooled chillers keeping in mind various factors.

Refrigeration engineer has to consider the ambient conditions (wet bulb and dry bulb), number of hours of operation, part load pattern and cost of maintenance etc.

HVAC experts have no single answer to when asked “water cooled chiller is better or air cooled chiller?”.

The fact is that “It all depends”.

Water-cooled chillers will normally condense at an average lower pressure than air-cooled chillers.

This is because the water temperature will usually be less than the air temperature.

If your condenser is operating at lower pressure then it is directly reflected and translated into lower operating costs or KW /TR(Ton of refrigeration).

The difference between the wet-bulb temperature and the dry-bulb temperature gives the available difference between the condensing temperatures of water-cooled and air-cooled condensers respectively.

Cooling towers and/or evaporative condensers have main disadvantage of maintenance and water treatment costs.

This running cost is not present in air cooled chillers.

Despite the advantages of lower IKW/TR of a water-cooled system or water cooled chillers, sometimes, air-cooled systems are preferred for various applications.

For example in 24 hour application of HVAC chillers,the night time dry bulb temperature are generally much lower than the day time dry bulb temperature, as compared to the difference in wet bulb temperature between day and night.

This advantage is best capitalized by an air-cooled system or air cooled chillers.

Other examples could be where the wet bulb temperatures are very high, especially coastal areas.

When comparing water cooled and air cooled chiller,scarcity of water and hence cost of water is another issue which is a point to be considered while deciding on the system.

This happens in many countries .

Space is also of importance in some applications.

Air cooled chillers can utilize open space, such as a parking lot, roof or ground level area.

Although smaller in size but Water cooled chillers require a mechanical room and cooling towers.

Air recirculation is very important for air cooled chillers.

Any obstruction in the circulation of air near water chillers would adversely affect the performance of air cooled chillers.

Air cooled chillers can have problems with recirculation if there are walls higher than the unit or too many units to close together.

If there is a situation where outside walls are required for building code and the unit will not be receiving enough fresh air, then a water cooled application may be the best option.

Water cooled chillers have longer life,higher efficiency,large capacity and also refrigerant containment.

While looking on disadvantatges of air cooled chillers,they have lower efficiency,comparatively short life span and available in low capacity range.

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The illustration below compares the operating cost of an air cooled variable speed centrifugal chiller versus a water cooled screw chiller.

This comparison is based upon a 140 ton load, weather data, $.07/kwh electrical costs, $5.00/1000 gallon water and sewer costs and 6,000 hrs/year operation.

Because the air cooled chiller uses floating head pressure control, the compressor energy costs are actually less than the water cooled chiller's compressor costs-a $4,757 difference ($20,585-$15,585).

Adding the tower system's operating cost of $17,429 results in a $22,186/year operating cost savings.

A more efficient variable speed water cooled centrifugal chiller reduces the cost difference to $16,725-still a significant annual cost penalty.

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Water-Cooled Chiller vs Air-Cooled Chillers

Difference

There are two types of Mri Chillers: Air-cooled chillers and Water-Cooled Chillers

What is the difference between an air cooled chiller and a water chiller?

These two terms have to do with how the chillers refrigeration system gets rid of the heat it removed from the water process loop.

In the case of an air-cooled chiller, heat is rejected to the ambient air.

In the case of a water-cooled chiller, heat is rejected to some other water source such as a cooling tower plant chilled water system.

water chillers

by

technolab el-bahaa group

general.dr

bahaa badr

water treatment consultant

01229834104

Water chillers are used for cooling mould to improve the smooth finish of plastic products and reduce the internal stress.

It is easy to demould plastic products and the output has been raised.

Water chillers are also used for cooling all kinds of lubricating oil and hydraulic transmission oil to control the oil temperature accurately and improve the processing accuracy.

chillers are developed on the basis of introducing and assimilating the products' merits from the Europe and America.

Utilizing imported efficient hermetic compressor, heat exchanger and multifunction controller,

chillers are easy to operate and maintenance.
Feature

Compact and completely sealed structure,

but high efficiency;

Easy installation

, operation and maintenance;

Adopts U.S.A. or Japan compressor and electronic parts to ensure long service life;

Adopts pipe type evaporator and condenser to enhance heat exchange efficiency;

Equipped with thermostatic expansion valve

, motor protection device, high/low pressure switch

, high pressure safety valve(or fusable insert) and alarm.

Featured Parts

Compressor -- TECUMSEH/France (<=12Hp), Copeland/USA(<=15Hp), Danfoss

Performer(<=25Hp);

Dryer Filter, Pressure Controller -- Danfoss/Denmark (Mexico);

Temperature Controller -- DEI/Taiwan;

Electrics -- Schneider/Shanghai;

Pressure Gauge -- Coconut Tree/Taiwan;

Chilled Water Pump -- DAB/Italy.

Specification

General Specification

Refrigerant: R22.

Controller: PLC with digital LED display.

Temperature of inlet cooling water (for water cooled type only): <=320C.

Temperature of circumstance (for air cooled type only): <=350C.

Temperature of outlet chilled water: 5~200C.

Power Supply: 380V/3p, 50Hz (or OEM).

Compressor: Swirl Rotation Type, Hermetic

Safety Device: High/low Pressure Switch, Freeze Protector, Overload Relay, etc..

Refrigerant Control: Capillary(<=KC05) or Thermostatic Expansion Valve(>KC05).

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