Question 1

What should I choose: a cooling tower, a dry cooler or a chiller?

Accepted Answer

Two numbers decide it: the fluid temperature your process needs, and the dry-bulb and wet-bulb temperatures at the site. A dry cooler can only cool to air temperature and always returns fluid warmer than the air. A cooling tower cools by evaporation, almost down to the wet-bulb. If the setpoint is at least wet-bulb plus 3–5 °C, a tower without a chiller is enough; in most of Russia that means 25 °C or higher. Below that you need a refrigeration machine, a chiller or an absorption chiller, and the tower or dry cooler rejects its heat. More in "Dry cooler, cooling tower or chiller"

Question 2

What is the difference between a chiller and a cooling tower?

Accepted Answer

A cooling tower cools water by evaporation. It has no compressor and cannot take the water below the wet-bulb. A chiller is a refrigeration machine: it delivers water colder than the outdoor air in any weather, from −15 to +20 °C at the outlet on NCT machines. It pays for that in electricity. For a 1,000 kW cooling duty, a wet tower without a chiller draws about 30–35 kW, while an air-cooled packaged chiller draws about 333 kW, roughly ten times more. More in "What is a chiller?"

Question 3

Can you supply a locally made replacement for an imported cooling tower, evaporative condenser or chiller?

Accepted Answer

Yes. We build cooling towers, dry coolers, evaporative condensers, chillers, pump skids and controls at our own NCT plant in Sertolovo near St Petersburg. The old unit's data sheet and nameplate help, but real operating data is more reliable: flow, inlet and outlet temperatures, load, fluid and location. If the old unit never held its duty, find the cause first: a new one on the same water and the same selection will fail the same way. One caveat on large centrifugal machines: nobody in Russia makes a centrifugal compressor in series yet. More in "Cooling equipment made in Russia"

Question 4

Dry cooler or cooling tower: which one?

Accepted Answer

A dry cooler, if the process accepts fluid noticeably warmer than outdoor air, water on site is scarce, or the loop must stay closed on glycol. It uses no water, needs no water treatment and is easier to maintain: the main task is keeping the glycol concentration right. A cooling tower is needed when you want colder water: it cools to the wet-bulb, which in a central Russian heat wave sits 7–10 °C below the dry-bulb. If a dry unit copes in winter but not in summer heat, add adiabatic pre-cooling or pair it with a tower. More in "Cooling tower vs dry cooler"

Question 5

What matters more: purchase price or cost of ownership?

Accepted Answer

Cost of ownership. The machine itself is 5–15% of all cooling costs over 15 years; electricity, service, repairs and downtime take the rest. A 1,000 kW chiller drawing about 300 kW around the clock uses about 2.6 million kWh a year. So compare options on total cost of ownership (TCO) over 10–15 years, and compare whole schemes over 15–20 years. The option that wins on purchase price often loses on TCO by a factor of 1.5–2. More in "Chiller total cost of ownership"

Question 6

How much does an industrial cooling tower or chiller cost?

Accepted Answer

We quote after a selection run: the price depends on capacity, temperatures, site climate, materials and scope. You can estimate the order in ratios. Taking an open tower as the base, a closed-circuit tower costs 1.8–2.5 times more and a dry unit 1.5–3 times more. A chiller with built-in free cooling costs about 15–25% more than a standard packaged unit. We prepare a technical proposal for your duty free of charge from a questionnaire. When comparing quotes from different suppliers, check they were sized for the same conditions, or you are comparing different machines. More in "Choosing a plant cooling system"

Question 7

Your cooling tower costs more than a cheap imported one. What am I paying for?

Accepted Answer

First check that you are buying the same thing. A 20% price gap between quotes usually hides a selection on different conditions, missing proper controls or no in-house service. See whether the quote states the design wet-bulb and the winter mode. Ask about the casing: cheap fiberglass or plastic cracks within 3–5 years, while hot-dip galvanizing of 80–120 µm with powder coating on both sides does not. And ask whether the manufacturer keeps spare parts and its own service team in the country. More in "Cooling tower selection: 13 mistakes"

Question 8

Can I see your equipment running and talk to the operators?

Accepted Answer

Yes. We provide a reference list of similar sites and arrange visits to running installations, and you can tour our whole plant in Sertolovo. This is the best supplier check: a website and certificates are easy to assemble, workshops and shipments are not. Ask for the chief engineer of a running site of the same capacity and call them: an online review is no substitute for a conversation. Also ask who does commissioning and service, in-house engineers or a subcontractor. More in "Cooling equipment made in Russia"

Question 9

Absorption chiller or electric compressor chiller: which one?

Accepted Answer

It depends on the heat available on site. With cheap or waste heat (steam, hot water from 80 °C, engine exhaust) or short grid capacity, and cooling needed 3,000–4,000 hours a year or more, look at an absorption chiller. For 1,000 kW of cooling, an absorption system needs 87 kW of electrical capacity against 245 kW for a chiller plant. With no heat, little cooling demand or a need below −5 °C, choose a chiller. A hybrid often wins: the absorption unit carries the base load, the chiller covers peaks and standby. Compare the cost of a kWh of cooling, not the COP. More in "Absorption or electric chiller"

Question 10

Will an absorption chiller pay off, and what goes into the calculation?

Accepted Answer

With cheap or waste heat, the price gap over a chiller usually pays back in 2.5–5 years; below about 500 kW a chiller is cheaper to buy. Count the whole scheme, not just the machine. A single-effect absorption chiller rejects about 2.45 kW of heat to the cooling tower per kW of cooling, against 1.2 kW for an electric chiller, so towers, pumps and plot area are larger. The calculation needs the heat source with its temperature and flow, the monthly cooling load and local tariffs. Run the numbers in the "Absorption vs chiller calculator"

Question 11

Will trigeneration (gas engine plus absorption chiller) pay off if the site still has enough grid capacity?

Accepted Answer

Not always. Trigeneration pays off when four conditions meet: gas is available with an allocation; electricity is expensive or the grid will not give capacity; heat and cooling are needed most of the year; and the load is long, 3,000–4,000 hours a year or more for the absorption chiller. Then the plant uses 85% of the fuel instead of 35–40%. If the site does not need its own power and cannot sell the surplus, the main gain is gone and the project may not pay back. Base the calculation on the site's real demand for power, heat and cooling. More in "Trigeneration: when it pays off"

Question 12

The cooling tower cannot hold the temperature in summer. Tower plus chiller, or chiller only?

Accepted Answer

Usually it pays to keep the tower and add a chiller. The tower does the job alone most of the year, and the machine works in summer and on the last few degrees. A large temperature drop is cheaper in two stages: when cooling from +80 to +15 °C, the tower removes about 75% of the heat for free, and the chiller comes out 3–4 times smaller. With a chiller only, the compressor carries the whole drop all year round. Compare the options on construction and operating costs together over the service life. More in the "Cooling system schemes atlas"

Question 13

Which pays better: an open tower, a closed-circuit tower or an adiabatic dry cooler?

Accepted Answer

An open tower is the cheapest to buy; a closed-circuit tower costs 1.8–2.5 times more. Running costs tell a different story. An open tower needs mandatory water treatment, chemicals and Legionella control. A closed tower keeps the process loop clean, needs simpler water treatment and runs dry in winter. An adiabatic dry cooler uses water only in hot hours but draws more power than an open tower, and untreated water corrodes its aluminium fins. The choice depends on the price of water, how clean the loop must be and how strong your operations team is. More in "Dry cooler, cooling tower or chiller"

Question 14

When does free cooling pay off?

Accepted Answer

When you need cooling in the cold months too: process cooling, data centers, year-round operations. In central Russia free cooling runs about 4,500 hours a year. On a year-round 1,000 kW load in Moscow with a 12/18 °C water schedule, it removes about 61% of compressor electricity and pays back in 2–4 seasons. Comfort cooling in offices gains almost nothing, because nobody needs cooling there in winter. Free cooling does not cut peak demand either: in summer the compressors carry the load again. More in "Chiller free cooling"

Question 15

What share of a plant's electricity goes to cooling, and where do I start saving?

Accepted Answer

Typically 10–40% of a plant's consumption, and up to 80–90% at breweries and meat plants. Start by measuring: annual consumption of the chiller plant in kWh, the monthly load profile and the water temperature the process really needs. Every unnecessary degree of cooling costs 1.8–4.0% of compressor power. Then rank the measures by payback: free cooling, a warmer water schedule, variable-speed drives, water treatment, heat recovery. More in "How to cut industrial cooling costs"

Question 16

How much electrical capacity does a chiller plant need, and how can I reduce it?

Accepted Answer

It depends on the scheme. For 1,000 kW of cooling, compressors draw about 333 kW in an air-cooled chiller, about 200 kW in a water-cooled one and about 167 kW in a centrifugal chiller on a cooling tower. A water-cooled scheme cuts peak demand by a factor of 1.7–2, and a wet tower without a chiller does the same job on 30–35 kW. Free cooling cuts annual consumption but not the peak. If you hit the grid limit, look at cooling towers, absorption chillers or trigeneration, and decide before paying for the grid connection. More in "Five cooling schemes"

Question 17

What machines suit a very large load: packaged units, centrifugal chillers or absorption chillers?

Accepted Answer

Air-cooled packaged units make sense up to 1–2 MW of cooling, where there is no water or no room for a tower. Above that, water-cooled machines on a cooling tower are better: operating costs are 20–40% lower. Among compressor machines, centrifugal ones are the most efficient: oil-free NCT NWCV chillers cover 229–7,033 kW with a COP of 6.01–6.85 at 7 °C leaving the evaporator and 30 °C entering the condenser. An absorption chiller is a separate option when heat is available or power draw is critical. Compare options on total plant power, fans and pumps included. More in "How to choose an industrial chiller"

Question 18

Which cooling system should I choose for a data center?

Accepted Answer

Capacity, supply temperature and the grid limit decide it. With 7 °C supply you cannot avoid a refrigerant chiller; at 10–18 °C a chiller with free cooling fits. At 25–35 °C, with liquid-cooled racks, the chiller can go and a closed-circuit cooling tower stays. Below 1,000 kW an ordinary compressor chiller is the honest choice; tower schemes start from there. If the grid gives no more than 1.5 times the IT load, you need schemes with a PUE of 1.2 or lower, or a gas-fired absorption chiller. Choose the scheme before paying for the grid connection. More in "Data center cooling: five options"

Question 19

What PUE does each data center cooling scheme achieve?

Accepted Answer

PUE is total data center energy divided by IT energy; the closer to 1, the less goes to cooling. The industry average is 1.6–1.8. A classic chiller scheme gives 1.45 and above, free cooling and cooling towers 1.20–1.35, a gas-fired absorption chiller 1.15–1.25, and direct-to-chip liquid cooling with a closed-circuit tower 1.06–1.12. The NREL record without mechanical chillers is 1.036. More in "AI hits the cooling wall"

Question 20

Will the equipment work properly in winter and in the shoulder seasons?

Accepted Answer

Yes, if it was selected for winter, so tell us the lowest outdoor temperature at the site when ordering. A standard chiller trips in frost and needs a winter kit; with it, NCT packaged chillers run down to −30 °C. Towers with a centrifugal fan at the bottom, such as the VR series, cannot ice up: the fan sits above a heated room. Closed-circuit towers switch off the spray at around +5 °C and run dry. Dry coolers are filled with glycol: water inside freezes the coil within hours if circulation stops in frost. More in "How to choose an industrial chiller"

Question 21

What if the equipment does not deliver the rated capacity?

Accepted Answer

You check it at acceptance, not on trust. The quote must state the design point: temperatures, fluid, outdoor air or wet-bulb. A chiller plant is handed over after integrated testing, usually 72 hours on the process load with data logging. For a cooling tower there is an acceptance test to CTI ATC-105 by an independent laboratory. At the plant, pump skids are pressure-tested and every absorption chiller gets a helium leak test. A quote without a design point is a warning sign before you sign anything. More in "Turnkey chiller plant contractor"

Question 22

Can we work without an advance payment, in case the supplier fails to deliver?

Accepted Answer

Yes. If company rules forbid advances, payment goes through a letter of credit: the bank holds the money until the supplier meets the terms. That adds 2–3% to the contract. The best check before paying is a visit to the plant and a call to the chief engineer of a running site of the same capacity. Our NCT plant in Sertolovo has been in production since 2014, and you can walk through all of it to see that you are dealing with the manufacturer. More in "Cooling equipment made in Russia"

Question 23

Can you select equipment from a photo, or can we use your selection software ourselves?

Accepted Answer

Not from a photo: a picture shows neither the load nor the temperatures. Our engineers do the selection from a questionnaire: flow and heat load, inlet and outlet temperatures, fluid (water or glycol and its concentration), climate and location, year-round or seasonal operation, redundancy. From it we prepare a free technical proposal for your duty. Figures in our design guides are for checking; the working figure comes from the technical proposal. More in our design guides for engineers

Question 24

Do you manufacture the equipment yourselves or just resell it? Can you supply the whole system?

Accepted Answer

We manufacture. Since 2014 our NCT plant in Sertolovo has built open and closed-circuit cooling towers, chillers, dry coolers, evaporative condensers, pump skids, tanks, water treatment panels and control panels. We do not make absorption chillers: Cold Energy (NCT) is the exclusive representative of Thermax in Russia and the CIS. You can buy the whole system as a turnkey chiller plant with single-point responsibility. A pump skid, for example, arrives as one module on a frame and connects on site at three points. More in "Turnkey chiller plant contractor"

Question 25

Our air-cooled condensers trip on high pressure when it is above +30 °C. Will evaporative condensers help?

Accepted Answer

Check cleanliness first: about 1 mm of dirt on the fins cuts condenser efficiency by 21% and raises consumption by 35%, the pressure climbs from 10 to 15 bar and the machine trips. An air-cooled condenser condenses 10–15 K above air temperature. Evaporative schemes work from the wet-bulb: with a wet cooling tower, condensing runs 8–12 K lower than with air, and every degree is worth 1.8–4.0% of compressor power. Never spray untreated water on air-cooled condenser fins: hardness salts eat the aluminium. More in the "Summer cooling readiness checklist"

Choosing a cooling system: questions and answers