The Components of an Air Conditioning System - Detailed Information About Compressors

The Components of an Air Conditioning System

 In this post we are going to see in detail, what are the different parts of any refrigeration or an air conditioning system, in details.

Basic Parts of an Air Conditioning (Refrigeration) System:

            A common refrigeration framework comprises of a few essential parts like Compressors, condensers, expansion valves, evaporators, and a few extras like controls, filters, driers, oil separators and so forth.. For proficient activity of the air conditioning system, it is fundamental that there should be a legitimate matching between different parts. Prior to investigating the adjusted execution of the total system, it is vital for concentrating on the design and execution qualities of individual parts. Besides in exceptional applications, the air conditioning parts are standard parts produced by businesses having some expertise in individual parts. For the most part for huge frameworks, contingent on the plan details, parts are chosen from the manufacturer indexes and are gathered at site. Despite the fact that the majority of the parts are standard off-the-rack things, here and there parts, for example, evaporator might be specially made. Little limit refrigeration systems for example, fridges, room and bundle climate control systems, water coolers are accessible as complete systems. For this situation the producer himself plans or chooses the framework parts, gathers them at the manufacturing plant, tests them for execution and afterward sells the complete framework as a single unit.

What are Compressors ?

        A Compressor is known as the heart of an Air conditioner. A Compressor is the most significant and frequently the costliest part (ordinarily 30% to 40% of absolute expense) of any vapor Compression refrigeration system. The capacity of a compressor in vapor Compression refrigeration system is to constantly draw the refrigerant from the evaporator, so that a low pressure and low temperature can be kept up with in the evaporator at which the refrigerant can change its face, removing heat from the refrigerated space. The blower then needs to raise the strain of the refrigerant to a level at which it can gather by dismissing hotness to the cooling medium in the condenser.

What are the Classifications of Compressor?

            Compressors utilized in refrigeration frameworks can be grouped in more than one way:

(First classification type) Based on the functioning standard:

            * Positive displacement type

            * Roto-dynamic type

        The Positive Displacement type of compressors, compression is accomplished by catching a refrigerant  into an encased space and afterward decreasing its volume. Since a proper measure of  refrigerant is caught each time, its pressure ascents as its volume is diminished. Whenever the strain ascends to a level that is marginally higher than the gathering pressure, then, at that point, it is ousted from the encased space and a new charge of low-pressure refrigerant is attracted and the cycle proceeds. Since the progression of refrigerant to the compressor isn't consistent, the positive displacement type of compressor is a throbbing stream gadget. Be that as it may, since the working velocities are typically exceptionally high the stream seems, by all accounts, to be practically consistent on perceptible time scale. Since the stream is throbbing on an infinitesimal time scale, positive displacement type compressor are inclined to high wear, vibration and noise level.

        Contingent on the development, positive displacement type of compressors utilized in refrigeration and furthermore in air conditioning, they can be categorized into:

* Reciprocating type

* Rotary type with sliding vanes (rolling piston type or multiple vane type)

* Rotary screw type (single screw or twin-screw type)

* Orbital compressors, and

* Acoustic compressors.

In roto-dynamic type of compressors, the pressure ascent of refrigerant is accomplished by conferring motor energy to a consistently streaming stream of refrigerant by a pivoting mechanical component and afterward changing over into pressure as the refrigerant moves through a veering entry. In contrast to positive dislodging type, the roto-dynamic sort of compressors are consistent stream gadgets, consequently are exposed to less wear and vibration.

Contingent on the development, roto-dynamic sort of compressors can be categorized into:

* Radial flow type and

* Axial flow type.

The Centrifugal type of compressors (otherwise called as turbo Compressors) are radial flow type, roto-dynamic Compressors. These Compressors are generally utilized in enormous limit refrigeration and air conditioning frameworks. Axial flow type of compressors are ordinarily utilized in gas liquification applications.

(Second classification type) In view of arrangement of compressor motor or outer drive:

        * Open type

        * Hermetic (or sealed) type

        * Semi-hermetic (or semi-sealed) type

In open type of compressors the alternating shaft of the blower stretches out through a seal in the

crankcase for an outside drive. The outside drive might be an electrical engine or a motor (for example

diesel motor). The blower might be belt driven or gear driven. Open type of compressors are

ordinarily utilized in medium to enormous limit refrigeration framework for all refrigerants and for

smelling salts (because of its contrariness with airtight engine materials). Open type of compressors

are described by high proficiency, adaptability, better compressor cooling and administration capacity.

Be that as it may, since the shaft needs to stretch out through the seal, refrigerant spillage from the framework can't be dispensed with totally. Consequently refrigeration frameworks utilizing open type of compressors require a refrigerant repository to deal with the refrigerant spillage for quite a while, and afterward customary upkeep for accusing the arrangement of refrigerant, changing of seals, gaskets and so on..

            In hermetic compressors, the engine and the blower are encased in a similar lodging to forestall refrigerant spillage. The lodging has welded associations for refrigerant channel and outlet and for power input attachment. Subsequently, there is basically no chance of refrigerant spillage from the compressor. All engines reject a piece of the power provided to it because of swirl flows and erosion, or at least, failures. Comparably the compressor additionally gets warmed up because of rubbing and  furthermore because of temperature climb of the refrigerant during pressure. In Open sort, both the compressor and the engine ordinarily reject hotness to the Surrounding air for productive activity. In hermetic compressors heat can't be dismissed to the encompassing air since both are encased in a shell. Subsequently, the cold suction gas is made to stream over the motor and  the compressor prior to entering the compressor. This keeps the motor cool. The motor winding is in direct contact with the refrigerant consequently just those refrigerants, which have high dielectric strength, can be utilized in hermetic compressors. The cooling rate relies on the stream pace of the refrigerant, its temperature and the warm properties of the refrigerant. In the event that stream rate isn't adequate and additionally in the event that the temperature isn't low sufficient the protection on the winding of the motor can wear out and shortcircuiting may happen. Subsequently, hermetically sealed compressors give palatable and safe execution over an extremely tight scope of plan temperature and ought not be utilized for off-plan conditions.

Reciprocating Type of Compressors:

            Reciprocating type of compressor is the workhorse of the refrigeration and cooling industry. It is the most broadly utilized compressor with cooling limits going from a couple of Watts to many kilowatts. Present day Reciprocating compressor are rapid (≈ 3000 to 3600 rpm), single acting, single or multi-chamber (upto 16 chambers) type. Reciprocating compressor comprise of a cylinder moving this way and that in a chamber, with pull and release valves to accomplish pull and pressure of the refrigerant. Its development and working are to some degree like a two stroke engine, as suction and

compression of the refrigerant are finished in one revolution of the crank. The suction side of the compressor is associated with the exit of the evaporator, while the release side of the compressor is associated with the condenser inway. The pull (inlet) and the release (outlet) valves open and close because of pressure contrasts between the chamber and inlet or outlet manifolds separately. The strain in the inlet complex is equivalent to or somewhat not exactly the evaporator pressure. Comparatively the pressure in the power source complex is equivalent to or marginally more noteworthy than the condenser pressure. The aim behind the manifolds is to give stable inway and, outlet pressures for the smooth activity of the valves and furthermore give a space for mounting the valves. The valves utilized are of reed or plate type, which are either drifting or clasped. Ordinarily, fences are given to restrict the valve uprooting and springs might be accommodated smooth return in the wake of opening or shutting. The cylinder piston speed is chosen by valve type. Too high a speed will give inordinate refrigerant vapor speeds that will diminish the volumetric effectiveness and the throttling loss will diminish the compression proficiency.

Rolling piston (fixed vane) type compressors:

            Rolling piston or fixed vane type of compressors are utilized in little refrigeration frameworks (upto 2 kW limit) like homegrown coolers or forced air systems. These compressors have a place in the class of positive displacement type as compression is accomplished by decreasing the volume of the refrigerant. In this kind of compressors, the alternating shaft of the roller has its pivot of turn that coordinates with the middle line of the chamber, in any case, it is flighty regarding the roller. This unpredictability of the shaft as for the roller makes pull and pressure of the refrigerant. A solitary vane or cutting edge is situated in the non-pivoting round and hollow square. The alternating movement of the roller causes a responding movement of the single vane This kind of compressor doesn't need a pull valve yet requires a release valve. The fixing between the high and low strain sides must be given, along the line of contact among roller and chamber block, along the line of contact among vane and roller, and in between the roller and end-pates. The spillage is controlled through hydrodynamic fixing and matching between the mating parts. The adequacy of the fixing relies upon the clearance, compressor speed, surface completion and oil thickness. Close resistances and great surface completing is expected to limit interior spillage. Not at all like in reciprocating compressors, the little clearance volume

loaded up with high-pressure refrigerant doesn't grow, however essentially blends in with the pull

refrigerant in the pull space. Accordingly, the volumetric effectiveness doesn't diminish radically with expanding pressure proportion, demonstrating little re-extension losses. The compressor moves along as expected and is somewhat calm as the refrigerant stream is ceaseless.

Multiple vane type of compressors:

            In multiple vane type of compressor, the hub of turn matches with the focal point of the roller, be that as it may, it is unusual regarding the focal point of the chamber. The rotor comprises of various spaces with sliding vanes. During the working of the compressor, the sliding vanes, which are typically made of non-metallic materials, are held against the chamber due to radial powers. The quantity of pressure strokes created in one revolution of the rotor is equivalent to the quantity of sliding vanes, consequently a 4-vane compressor produces 4 compression strokes in a single revolution. In these type of compressors, fixing is expected between the vanes and chamber, between the vanes and the spaces on the rotor and between the rotor and the end plate. Be that as it may, since pressure contrast across each opening is just a small portion of the complete pressure difference, the fixing isn't so basic as in fixed vane type of compressor.

            This kind of compressor doesn't need pull or release valves, nonetheless, check valves are utilized on release side to forestall invert turn during off-time due to pressure distinction. Since there are no release valves, the packed refrigerant is opened to the release port when it has been compacted through a decent volume proportion, contingent on the calculation. This suggests that these compressors have a fixed inherent volume proportion. The implicit volume proportion is characterized as "the proportion of a cell as it is shut off from the suction port to its volume before it opens to the release port". Since no divergent power is available when the compressor is off, the different vanes won't be squeezed against the chamber dividers during the off-period. Thus, high tension refrigerant from the release side can stream once more into the side and pressure balance among high and low pressure sides happen. This is advantageous according to the compressor engine perspective as it decreases the necessary beginning force. In any case, this acquaints cycling loss due with the section of high pressure and hot refrigerant fluid into the evaporator. Henceforth, regularly a non-return check valve is utilized on the release side which keeps the passage of refrigerant fluid from high strain side into

evaporator through the compressor during off-time, simultaneously there will be pressure

adjustment across the vanes of the compressor.

Rotary Screw type of Compressors:

            The rotary screw type of compressors can be of twin-screw type or single-screw type compressors.

Twin Screw type of Compressors:

            The twin-screw type of compressor comprises of two mating helically scored rotors, one male and another is the female. In General, the male rotor drives the female rotor. The male rotor has flaps, while the female rotor has woodwinds or chasms. at the point when the male rotor pivots at 3600RPM, the female rotor turns at 2400 RPM. The stream is chiefly in the pivotal course. Suction and

compression happens as the rotors unmesh and network. Whenever one flap chasm mix starts to unmesh, the contrary projection chasm mix starts to mesh.With 4 male flaps pivoting at 3600 RPM, 4 interlobe volumes are per revolution, accordingly giving 4 X 3600 = 14400 discharge each minute. Discharge happens at a point chosen by the planned inherent volume proportion, which

relies totally upon the area of the conveyance port and math of the compressor.

            In the event that the underlying pressure towards the finish of pressure is not exactly the gathering pressure, high pressure refrigerant from releases complex streams once more into the  interlobe space, when therelease port is revealed. This is known as under compression. Then again, if the underlying pressure towards the finish of pressure is higher than the consolidating pressure, then, at that point, the compacted refrigerant surges out in an over the top development when the port is

uncovered (over-compression). Both under-compression and over-compression are bothersome as they lead to losses in proficiency. Oil and seals between the rotors is acquired by infusing greasing up oil between the rotors. The oil additionally helps in cooling the compressor, subsequently extremely high pressure proportions (upto 20:1) are conceivable without overheating the compressor. The limit of the screw compressor is typically controlled with the assistance of a slide valve. As the slide valve is opened, some measure of suction refrigerant departures to the suction side without being compacted. This yields a smooth limit control from 100% down to 10% of full load. It is seen that the power input is roughly relative to refrigeration limit upto around 30%, in any case, the proficiency diminishes quickly, there later. It tends to be seen that for a given worked in volume proportion, the effectiveness arrives at a top at a specific ideal strain proportion. The worth of this ideal strain proportion increments with worked in volume proportion. On the off chance that the plan condition relates to the ideal pressure proportion, the pressure proficiency drops as the framework works at off-plan conditions. Nonetheless, when worked at the ideal pressure proportion, the effectiveness is a lot higher than other

sorts of compressors. 

            As the rotor ordinarily turns at high velocities, screw compressors can deal with genuinely enormous measures of refrigerant stream rates contrasted with other positive dislodging type

compressors. Screw compressors are accessible in the limit scope of 70 to 4600 kW. They, for the most part contend with high limit responding compressors and low limit radial compressors. They are accessible for a wide assortment of refrigerants and applications. Contrasted with reciprocating type of compressors, screw compressors are adjusted and consequently don't experience the ill effects of vibration issues. Twin-screw blowers are rough and are demonstrated to be more solid than reciprocating type of compressors; they are displayed to run for 30000 - 40000 hours between significant upgrades. They are reduced contrasted with reciprocating type of compressors in the high limit range.

Single screw type of Compressors:

            As the name infers, single screw compressors comprise of a solitary helical screw and two planet wheels or entryway rotors. The helical screw is housed in a barrel shaped packaging with suction port toward one side and release port at the opposite end. Suction and compression are acquired as the screw and entryway rotors unmesh and network. The high and low pressure areas in the chamber packaging are isolated by the entryway rotors. The single screw is ordinarily determined by an electric motor. The entryway rotors are ordinarily made of plastic materials. Tiny power is expected to pivot the door rotors as the frictional losses between the metallic screw and the plastic door rotors is tiny. It is likewise conceivable to plan the compressors with a solitary entryway rotor. Like twin-screw, grease, fixing and compressor cooling is accomplished by infusing greasing up oil into the compressor. An oil separator, oil cooler and siphon are expected to course the greasing up oil. It is additionally conceivable to accomplish this by infusing fluid refrigerant, in which case there is no requirement for an oil separator. 

Scroll type of Compressors:

            Scroll compressors have orbital movement, positive displacement type of compressors, in which

suction and compression is acquired by utilizing two mating, spiral molded, scroll individuals, one fixed and the other circling. The compression process includes three circles of the circling scroll. In the principal circle, the parchments ingest and trap two pockets of suction gas. During the subsequent circle, the two pockets of gas are compacted to a transitional pressure. In the last circle, the two pockets reach release pressure and are all the while opened to the release port. This synchronous interaction of suctions, moderate compression, and release prompts the smooth persistent compression interaction of the Scroll compressor. One section that isn't displayed in this outline yet is fundamental for the activity of the scroll is the anti-rotation coupling. This gadget keeps a proper rakish connection of 180 degrees between the fixed and circling scrolls. This fixed rakish connection, combined with the development of the circling scroll, is the reason for the arrangement of gas pressure pockets. At present, the Scroll compressors are utilized in little limit (3 to 50 kW) refrigeration, air conditioning and hotness siphon applications. They are ordinarily of airtight kind. Scroll compressors offer a few benefits, for example, Huge suction and release ports diminish pressure losses during suction and release. Actual division of suction and compression diminish heat move to suction gas, prompting high volumetric effectiveness. Volumetric effectiveness is additionally high because of extremely low re-extension losses and persistent stream over a wide scope of working circumstances. Compliment limit versus open air temperature bends. High pressure productivity, low clamor and vibration contrasted with responding

compressors. Reduced with least number of moving parts, each scroll part is open toward one side and limited by a base plate at the other end. They are fitted to frame pockets of refrigerant between their individual base plates and different lines of contacts between the scroll dividers. compressor limit is ordinarily constrained by factor speed inverter drives.

Centrifugal type of Compressors:

            These type of compressors are widely used due to their extensive advantages over other type of compressors. Centrifugal compressors, otherwise called turbo compressors, have a place with the roto-dynamic sort of compressors. In these type of compressors the expected pressure ascent happens due to the consistent change of precise force conferred to the refrigerant by a high speed impeller into static strain. Dissimilar to reciprocating compressors, centrifugal compressors are consistent stream gadgets henceforth they are exposed to less vibration and noise. Low pressure refrigerant enters the compressor through the eye of the impeller. The impeller comprises of various cutting edges, which structure stream sections for the refrigerant. From the eye, the refrigerant enters the stream sections framed by the impeller edges, which pivot at extremely fast. As the refrigerant moves through the edge entries towards the tip of the impeller, it acquires energy and its static pressure additionally increments. From the tip of the impeller, the refrigerant streams into a fixed diffuser. In the diffuser, the refrigerant is decelerated and accordingly the unique strain drop is changed over into static pressure ascent, subsequently expanding the static pressure further. The refrigerant from the diffuser enters the volute packaging where further transformation of speed into static pressure happens because of the disparate state of the volute. At last, the compressed refrigerant leaves the compressor from the volute packaging. The increase in force is because of the exchange of energy from the high velocity impeller sharp edges to the refrigerant restricted between the edge entries. The expansion in static pressure is because of the self-pressure brought about by the radiating activity. This is closely resembling the gravitational impact, which makes the liquid at a more elevated level press the liquid underneath it because of gravity (or its weight). The static pressure delivered in the impeller is equivalent to the static head, which would be delivered by an identical gravitational segment. In this way it tends to be seen that for a given refrigerant with a decent thickness, the strain rise relies just upon the fringe speed or tip speed of the sharp edge. The tip speed of the sharp edge is corresponding to the rotational speed (RPM) of the impeller and the impeller distance across. The most extreme admissible tip speed is restricted by the strength of the primary materials of the edge (generally made of fast chrome-nickel steel) and the sonic speed of the refrigerant. Under these limits, the greatest reachable pressure ascent (henceforth

most extreme feasible temperature lift) of single stage radial compressor is restricted for a

given refrigerant. Consequently, multistage Centrifugal compressors are utilized for enormous temperature lift applications. In multistage radiating compressors, the release of the lower stage

compressor is taken care of to the inlet of the next following stage compressor, etc. In multistage

centrifugal compressors, the impeller measurement of all stages stays same, yet the width of

the impeller turns out to be continuously smaller toward stream as refrigerant thickness

increments logically.

                        The blades of the compressor are either forward bended or in reverse bended or spiral.

Reverse bended blades were utilized in the more seasoned compressors, while the cutting edge centrifugal compressors utilize for the most part outspread radial blades. The fixed diffuser can be vaned or vaneless. As the name infers, in vaned diffuser vanes are utilized in the diffuser to shape stream entries. The vanes can be fixed or flexible. Vaned diffusers are conservative contrasted with the vaneless diffusers and are normally utilized for high release pressure applications. Be that as it may, the presence of vanes in the diffusers can bring about shocks, as the refrigerant speeds at the tip of the impeller cutting edge could reach sonic speeds in enormous, high velocity centrifugal compressors. In vaneless diffusers the speed of refrigerant in the diffuser reductions and static pressure increments as the range increments. Thus, for a necessary pressure ascent, the expected size of the vaneless diffuser

could be huge contrasted with vaned diffuser. Be that as it may, the issue of shock due to supersonic speeds at the tip doesn't emerge with vaneless diffusers as the speed can be diffused without a hitch.

For the most part customizable aide vanes or pre-revolution vanes are added at the inlet (eye) of the

impeller for limit control.

                Industrially centrifugal compressors are accessible for a wide assortment of refrigeration and

cooling applications with a wide assortment of refrigerants. As referenced previously, on the lower side the limit is restricted by the impeller width and tipspeeds and on the higher side the limit is restricted by the actual size (as of now the most extreme impeller breadth is around 2 m). Since the presentation of centrifugal compressors is more touchy to evaporator and consolidating temperatures contrasted with a reciprocating compressor, it is fundamental to lessen the pressure drops when a centrifugal compressor is utilized in business frameworks. Business refrigeration frameworks utilizing radial compressor typically consolidate streak intercoolers to further develop the framework execution. Since the compressor is ordinarily multistaged, utilization of blaze intercooler is moderately simple if there should be an occurrence of centrifugal compressors. centrifugal compressors are ordinarily greased up utilizing an oil siphon (forcibly feed) which can be driven either straight by the compressor rotor or by an outer motor. The oil framework comprises of the oil siphon, oil repository and an oil cooler. The parts requiring oil are the primary heading, a push bearing (for the adjusting circle) and the shaft

seals. Contrasted with reciprocating, the oil for centrifugal compressors is streamlined as very little greasing up oil comes in direct contact with the refrigerant. Ordinarily maze type oil seals are utilized on the rotor shaft to limit the spillage of greasing up oil to the refrigerant side. Now and again oil warmers might be expected to stay away from unnecessary weakening of greasing up oil during the plant closure. Industrially both airtight as well as open sort diffusive blowers are accessible.

Open sort of compressors are driven by electric motors, gas powered motors (utilizing a wide assortment of fills) or even steam turbines.

                I hope this article is helpful and has increased your knowledge about different types of compressors.

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