Cooling System Schemes Atlas: 31 Piping Diagrams, Tower to Heat Pump

The atlas collects 31 schematic diagrams of cooling and heating systems on 45 pages, from the simplest open cooling tower to an absorption heat pump that lifts waste heat to +90 °C. Each diagram shows the full piping you actually design and install from: pumps, isolation valves, strainers, check valves, expansion tanks, temperature and pressure sensors. Next to it: how the system works in plain words, pros and cons, where it is used, and a photo of our equipment. It is written both for design engineers and for managers choosing a system for their site. The Russian-language PDF is available in my Telegram channel "Maxim, I need cooling"; the key points are below in English.

What is inside the atlas?

• A 3-page glossary: what is what on the diagrams.

• "Choose a scheme in 2 minutes": a selection table by required outlet temperature.

• Selection trees by NCT product series: free cooling first, then the choice between a vapour-compression chiller and an absorption chiller.

• Scheme 1. Open cooling tower, direct: 45–65 °C circulating water, the cheapest kilowatt of cooling.

• Scheme 2. Open cooling tower + plate heat exchanger: a clean loop for induction furnaces and lasers.

• Scheme 3. Closed cooling tower without a chiller: wet-bulb +4–5 °C with no compressors, liquid-cooled data centers.

• Scheme 4. Dry cooler: no water, setpoints from +18 °C.

• Scheme 5. Adiabatic dry cooler: covers 100–300 hot hours a year without a chiller.

• Scheme 6. Water-cooled chiller + open cooling tower: the best COP among compressor schemes.

• Scheme 7. Water-cooled chiller + closed cooling tower: a clean condenser loop.

• Scheme 8. Packaged air-cooled chiller: the most common scheme, +12/+7 °C.

• Scheme 9. Chiller with built-in free cooling: compressors stop in winter.

• Scheme 10. Chiller with remote condenser: machine room inside, condenser on the roof, refrigerant line up to 50 m.

• Scheme 11. Chiller + free-cooling dry cooler + plate heat exchanger: two machines back each other up.

• Scheme 12. Chiller with heat recovery: cooling plus domestic hot water at +45–50 °C from one machine.

• Scheme 13. Chiller + thermal storage tank: ice water at 0 to +2 °C for peaks.

• Scheme 14. Low-temperature glycol chiller: −18 to −8 °C, freezing and ice rinks.

• Scheme 15. Ammonia chiller + evaporative condenser: industrial freezing from about 1 MW.

• Scheme 16. Absorption chiller + compression chiller cascade: waste heat for low-temperature cooling.

• Scheme 17. Hot-water absorption chiller, 85–130 °C: cooling with almost no electricity.

• Scheme 18. Two-stage steam absorption chiller: loads the boiler house in summer.

• Scheme 19. Direct-fired gas absorption chiller: gas on site, no spare grid capacity.

• Scheme 20. Trigeneration, gas engine + absorption chiller: power, heat and cooling from one cubic metre of gas.

• Scheme 21. Cooling tower with mixing + chiller: +80 to +15 °C for quenching, rolling, furnaces.

• Scheme 22. Dry cooler + chiller in two stages: the same range with no water use.

• Scheme 23. Hydraulic separator + pump groups: different consumers on one source.

• Scheme 24. Primary-secondary (decoupled): multi-chiller plants.

• Scheme 25. Series counterflow: two chillers for a +12 to 0 °C range.

• Scheme 26. Buffer tank: protection against short cycling in small loops.

• Scheme 27. Variable flow + pump VFDs (variable frequency drives).

• Scheme 28. N+1 / 2N redundancy: data centers, pharma, continuous production.

• Scheme 29. Reversible heat pump: +7 °C in summer, +45 °C heating in winter.

• Scheme 30. Absorption heat pump on low-pressure steam: waste heat up to +65 °C.

• Scheme 31. Absorption heat pump on high-pressure steam: up to +90 °C for a district heating network.

• Four typical piping mistakes.

• All schemes on one page: outlet temperature, power use, water use, when to choose.

Flows on the diagrams are calculated for a 1,000 kW load; for your site, scale them proportionally.

Key takeaways

The choice starts with the wet-bulb temperature. It is the limit to which water can be cooled by evaporation. For central Russia the design wet-bulb is about +21 to +23 °C. If the process accepts fluid warmer than wet-bulb +3 °C, free cooling is enough: schemes 1–5, the simplest and cheapest. If you need it colder, you cannot avoid mechanical cooling (schemes 6–20).

Free cooling uses 8–10 times less electricity, but the weather sets the limit. A dry cooler delivers fluid 5–7 K above the outdoor air: at +30 °C outside you get +35 to +37 °C. A closed cooling tower goes down to wet-bulb +4–5 °C, about +25 to +26 °C even at the peak of a central-Russian summer. An adiabatic dry cooler uses water only in the hottest hours: tens of cubic metres a year, not thousands as a cooling tower does.

The right comparison is not "chiller vs absorption chiller" but compression vs absorption. Both make cooling, only from different energy. A hot-water absorption chiller at 85–130 °C, with its piping pumps and cooling tower, draws 15–30 kW per 1 MW of cooling against about 300 kW for a compressor chiller of the same capacity. The price: a cooling tower 2.3–2.5 times larger than the cooling load and about 30 minutes to reach operating mode. The absorption chiller limit for the chilled fluid is about +4 to +5 °C.

A cold condenser is the main saving in compressor cooling. A water-cooled chiller on cooling tower water uses 25–35% less than an air-cooled packaged unit. Built-in free cooling in central Russia gives 4–6 months of free cooling a year: seasonal COP rises from 3 to 5–7 and electricity savings reach 30–50%, while the machine costs 15–25% more than a standard one.

A large temperature range is cheaper to remove in two stages. If water leaves the process at +80 °C and you need +15 °C, the cooling tower removes about 75% of the load by evaporation for free, and the compressors work only on the last 10 K out of 65. The chiller ends up 3–4 times smaller than for cooling the whole range in one stage.

Condenser heat does not have to be thrown away. For every kilowatt of cooling a chiller rejects about 1.25 kW of heat. A heat recovery exchanger warms domestic hot water to +45–50 °C and pays back in one heating season, if cooling and hot water are needed at the same time.

Pumps save by the cube law. Pump power is proportional to the cube of flow: 20% less flow cuts power use almost in half. Variable flow with VFDs saves 30–60% on pumping.

Four piping mistakes travel from project to project. A strainer after the pump instead of before it; an expansion tank on the discharge side instead of the suction side; parallel pumps without check valves, so flow circulates back through the idle standby pump; units without isolation valves, so replacing a pump means draining the whole system. All four come from real projects we had to rework during commissioning.

Who is it for?

• Design engineers and process engineers who need correct piping for a chosen scheme.

• Chief engineers and plant energy managers comparing options by electricity and water costs.

• Managers who need to see quickly which family of systems fits their site.

• Data center teams choosing between dry coolers, closed cooling towers, free cooling and N+1 / 2N redundancy.

FAQ

Where can I get the cooling system schemes atlas?

The atlas is distributed only through my Telegram channel "Maxim, I need cooling". The channel also publishes reviews of real projects built on these schemes, with CAPEX and OPEX figures.

How do I tell quickly whether I need a chiller?

Compare the outlet temperature you need with the wet-bulb temperature for your region. If a temperature above wet-bulb +3 °C is acceptable, free cooling with a cooling tower or dry cooler will do. If you need it colder, you need a chiller or an absorption chiller.

Can the diagrams go straight to installation?

No. The diagrams are schematic: they show what the piping consists of, while the exact specification is done in the design for your site. Flows are calculated for a 1,000 kW example and scale proportionally for other loads.

Related articles

• How to cut industrial cooling costs: 8 measures with the numbers

• Cooling tower vs dry cooler: which to choose for equipment cooling

• What is a chiller? How it works, main parts, layout and types

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