Approx­i­mate­ly 10 years ago, in our coun­try, first a sin­gle, then a wide prac­ti­cal use of air con­di­tion­ers began to cre­ate com­fort­able con­di­tions in rooms for var­i­ous pur­pos­es. In the vast major­i­ty of cas­es, these were split sys­tems, it was often pos­si­ble to observe how up to two hun­dred of their out­door units appeared on the facades of recon­struct­ed admin­is­tra­tive build­ings. Split sys­tems can­not main­tain the giv­en gas com­po­si­tion of air in the room, reg­u­late its humid­i­ty. Their main func­tion is air cool­ing.

Lat­er, for objects such as hotels, busi­ness cen­ters and oth­er sim­i­lar build­ings that require a cer­tain micro­cli­mate for their oper­a­tion, vapor-com­pres­sion water-cool­ing machines (PKHM), sup­ply cham­bers for sup­ply­ing fresh out­side air and fan coils began to be used.

Now the demand for refrig­er­a­tion for air con­di­tion­ing sys­tems con­tin­ues to grow. The required cool­ing capac­i­ty for new large facil­i­ties, such as water parks, shop­ping and enter­tain­ment cen­ters with an area of ​​30,000 — 100,000 m 2 , stor­age areas of logis­tics ter­mi­nals for the pro­cess­ing of phar­ma­ceu­ti­cal prod­ucts, loose tea and tobac­co increas­es to 5,000 — 8,000 kW. The use of vapor com­pres­sion machines at such facil­i­ties gives rise to a num­ber of tech­ni­cal prob­lems, the solu­tion of which sig­nif­i­cant­ly increas­es the cost of pro­duc­ing “cold”.

It should be not­ed that the role of air con­di­tion­ing sys­tems for the men­tioned objects is also increas­ing. From sys­tems that only pro­vide com­fort­able con­di­tions in the premis­es, they become part of the tech­no­log­i­cal process for them. So, every minute of a per­son­’s stay in a shop­ping cen­ter increas­es his income, so spe­cial tech­nolo­gies are being devel­oped to keep cus­tomers in the hall. And air con­di­tion­ing sys­tems no longer exist as an addi­tion­al option — they con­tribute to the devel­op­ment of the prof­itabil­i­ty of enter­pris­es and become one of the main tech­no­log­i­cal sys­tems.

We can assume that the trend of growth in the area of ​​a sin­gle con­struc­tion object has final­ly been deter­mined. The appear­ance of super-large objects in Moscow, and then in St. Peters­burg, indi­cates that over the next 3–5 years this trend will spread to oth­er Russ­ian cities. Thus, if the con­struc­tion of facil­i­ties with an area of ​​30,000 — 100,000 m 2 becomes a trend, it is use­ful to devel­op a prin­ci­pled approach to the refrig­er­a­tion sys­tems of these facil­i­ties.

All engi­neer­ing sys­tems of any object are con­nect­ed with each oth­er either func­tion­al­ly or through a con­trol sys­tem. Con­sid­er­ing options for solv­ing the prob­lem of refrig­er­a­tion sup­ply, it is nec­es­sary first of all to take into account how the issues of heat and elec­tric­i­ty sup­ply are resolved. The prob­lem of heat sup­ply of large objects is usu­al­ly solved by installing an autonomous boil­er house. The solu­tion to the prob­lem of pow­er sup­ply, and we are talk­ing about megawatts of elec­tric pow­er, is extreme­ly dif­fi­cult and expen­sive to solve. In the event that the facil­i­ty is equipped with an autonomous gas boil­er, then for refrig­er­a­tion sys­tems with a required cool­ing capac­i­ty of 500 kW there is an uncon­test­ed solu­tion — absorp­tion chillers (ABHM).

Popular Models


Daikin
Absorp­tion refrig­er­a­tion units York 14SC

Daikin
Absorp­tion cool­ers and cool­ing units Robur

Daikin
Absorp­tion chillers Lessar LUC-HWAR‑L

Absorp­tion Chillers: all mod­els

The first and main advan­tage of the absorp­tion refrig­er­a­tion machine is that it does not con­sume elec­tric­i­ty for the imple­men­ta­tion of the refrig­er­a­tion cycle. Elec­tric­i­ty is con­sumed only for the move­ment of media — the oper­a­tion of pumps and fans. In this case, the point is not that elec­tric­i­ty is expen­sive for the con­sumer, but whether it is pos­si­ble to con­nect to the grid, and if pos­si­ble, the cost of “con­nect­ing to the grids” of JSC “Lenen­er­go” in some cas­es reach­es 1000 US dol­lars per 1 kW . Sim­i­lar prob­lems may arise in oth­er cities sup­plied with elec­tric­i­ty from RAO UES of Rus­sia.

The next advan­tage is eco­nom­ic. As can be seen from Table 1, the ini­tial invest­ment costs for absorp­tion chillers are sig­nif­i­cant­ly low­er than those for vapor com­pres­sion chillers. From the ratio of oper­at­ing costs (see Table 2), the sec­ond impor­tant con­clu­sion fol­lows: the oper­a­tion of absorp­tion machines is almost two times cheap­er than the oper­a­tion of vapor com­pres­sion machines. The impor­tance of this con­clu­sion will become clear­er if we bear in mind that, accord­ing to the reg­u­la­tions, machines will oper­ate for 20 years before a major over­haul.

It was not­ed above that ABKhM works on hot water sup­plied
from an autonomous boil­er house, which is usu­al­ly turned off dur­ing the warm sea­son. The oper­a­tion of the absorp­tion refrig­er­a­tion plant increas­es the load fac­tor of the boil­er house, thus reduc­ing its pay­back peri­od, which in turn increas­es the effi­cien­cy of the invest­ment.

Anoth­er impor­tant advan­tage of absorp­tion machines is the low noise lev­el dur­ing their oper­a­tion. The intrin­sic noise lev­el of absorp­tion plants with a pow­er of up to 1500 kW does not exceed 65 dBa. In addi­tion, they meet the require­ments of the Mon­tre­al and Kyoto pro­to­cols, i.e. do not con­tribute to the destruc­tion of the ozone lay­er and glob­al warm­ing. absorp­tion machines do not use refrig­er­ants, the leak­age of which is the cause of the destruc­tion of the ozone lay­er.

From the mate­r­i­al of the arti­cle, the read­er may form an opin­ion about the pres­ence of some kind of panacea in the field of refrig­er­a­tion: cheap, sim­ple, envi­ron­men­tal­ly friend­ly and almost silent. All this is true. How­ev­er, there are some “buts”. Absorp­tion refrig­er­a­tion units have a greater mass than vapor com­pres­sion ones, and this mass must be dis­trib­uted when placed on the roof of a build­ing. The ABKhM cir­cuit includes a cool­ing tow­er of sig­nif­i­cant size and weight, the oper­a­tion of which is accom­pa­nied by noise, then silencers and acoustic screens may be nec­es­sary in res­i­den­tial areas. In some cas­es, instead of cool­ing tow­ers, func­tion­al and dec­o­ra­tive foun­tains are arranged. How­ev­er, the cost of the foun­tain exceeds the cost of the cool­ing tow­er. A cool­ing tow­er or foun­tain requires make-up water to oper­ate. For our exam­ple, the max­i­mum make-up water flow is up to 3.4 m 3 /h It also needs to be received and sub­mit­ted.

Thus, it becomes obvi­ous that reduc­ing invest­ment costs by almost three times, and oper­at­ing costs by about two times, is not as easy as it might seem at first glance. How­ev­er, there are some inter­est­ing engi­neer­ing solu­tions to over­come some of the incon­sis­ten­cies when con­sid­er­ing the whole com­plex of build­ing engi­neer­ing sys­tems, rather than an iso­lat­ed refrig­er­a­tion sup­ply sys­tem.

And the last. The absorp­tion tech­nique, which is real­ly attrac­tive to investors, also has a cer­tain social com­po­nent. Reduc­ing invest­ment and short­en­ing the pay­back peri­od of the project unwit­ting­ly con­tributes to low­er prices in the con­sumer mar­ket, in which the devel­op­ment engi­neer him­self acts as a buy­er of goods and ser­vices.

Table 1. Com­par­i­son of the ini­tial cost of a para­com­pres­sion refrig­er­a­tion machine (PKHM) and an absorp­tion refrig­er­a­tion machine (ABHM) with a cool­ing capac­i­ty Q o =1000 kW

Para­com­pres­sion refrig­er­at­ing machine (PKHM)

Absorp­tion chiller (ABHM)

Price

Approx­i­mate­ly $200 per 1 kW

Total: $200x1000= $200000

ABHM for 1000 kW — $150,000

Cool­ing tow­er — 15% of the cost of ABCM

Total: 50000+15%x150000= $172500

Addi­tion­al expens­es

Cool­ing coef­fi­cient:
ε=3.0

Required elec­tri­cal pow­er:
N e =Q o /ε=1000/3≈330 kW,

Total cost of con­nec­tion to the pow­er grid:
330x$1000= $330,000

If all invest­ments in an autonomous boil­er house have already been made, no addi­tion­al costs are required

Total

$330000+$200000= $530000

$172500

Table 2. Com­par­i­son of oper­at­ing costs when using a para­com­pres­sion refrig­er­a­tion machine (PKHM) and an absorp­tion refrig­er­a­tion machine (ABKhM) with a cool­ing capac­i­ty Q o =1000 kW

In both options, the elec­tric­i­ty con­sump­tion of pumps and fans (they should be approx­i­mate­ly equal) is not tak­en into account

Para­com­pres­sion refrig­er­at­ing machine (PKHM)

Sin­gle stage absorp­tion chiller

Tak­ing the inte­gral load of the refrig­er­a­tion machine equal to 0.5 of the nom­i­nal refrig­er­a­tion capac­i­ty (exclud­ing night time, week­ends), we deter­mine the costs for the oper­a­tion of the PCM, based on the cost of elec­tric­i­ty 1.45 rubles / kWh.

They make up ≈ RUB 689,000

Sin­gle stage hot water absorp­tion chillers with t w u003d 90.98 ° С, have a ther­mal coef­fi­cient

ς = Q 0 /Q G = 0.75,

where Qg is the amount of heat enter­ing the machine from the heat­ing medi­um.

It fol­lows that in an autonomous boil­er house it is nec­es­sary to burn a cer­tain vol­ume of nat­ur­al gas to obtain this amount of heat, name­ly:

Q G = Q 0 / 0.75 u003d 1,000 / 0.75 u003d 1330 kW.

Assum­ing the effi­cien­cy of the boil­er house equal to 0.9 with the calorif­ic val­ue of nat­ur­al gas ≈ 35,000 kJ/m 3 we deter­mine the total gas con­sump­tion for the warm peri­od of the year:

V = 1330 × 120 × 0.5 × 3600/35000 = 197,000 m 3 ,

those. prac­ti­cal­ly the con­sump­tion of nat­ur­al gas for the entire warm peri­od of the year is 200,000 m 3 . At a gas cost of 1.85 rubles. per m 3 its cost will be RUB 370,000

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