How does a chiller work? It moves heat rather than destroying it. A compressor, condenser, expansion valve and evaporator run a refrigerant loop that pulls heat out of a coolant reservoir, and a separate pump pushes that chilled fluid through your reactor jacket or condenser and carries the heat back. The loop repeats until your setpoint holds.<\/p>\n
We build the DLSB sealed recirculating chiller family, so the rest of this page is written from the parameter sheet we ship with those units rather than from an HVAC textbook. Where our sheet does not publish a number, we say so instead of inventing one.<\/p>\n
Every compressor-based chiller, from a building’s rooftop unit down to a bench box, runs the same four-stage cycle. Understanding it takes about two minutes and saves you from most sizing mistakes.<\/p>\n
Compressor.<\/strong> It takes low-pressure refrigerant vapour and squeezes it. Pressure goes up, and so does temperature \u2014 the vapour leaves the compressor hotter than the room. This is the only stage where you pay for electricity in a meaningful way, which is why the power rating on a chiller’s plate is essentially the compressor’s appetite plus the pump.<\/p>\n Condenser.<\/strong> Hot high-pressure vapour hits a finned coil with a fan blowing across it. Room air carries the heat away, and the refrigerant condenses into a liquid. This is where the heat you removed from your reaction actually ends up: in your lab. A chiller is a heat pump, not a heat destroyer, so a poorly ventilated cabinet will slowly cook the unit’s own condenser and drag its performance down.<\/p>\n Expansion valve.<\/strong> The liquid is forced through a restriction. Pressure drops hard, and the liquid flashes into a cold low-pressure mix. No electricity is used here; the temperature drop is paid for by the pressure drop you bought at the compressor.<\/p>\n Evaporator.<\/strong> The cold refrigerant runs through a coil sitting in the coolant reservoir. Heat flows from the coolant into the refrigerant, the refrigerant boils back to vapour, and the coolant gets colder. The vapour returns to the compressor and the cycle closes.<\/p>\n That is the whole trick. On our DLSB units the reservoir side reaches -30 \u00b0C to room temperature, and a PT100 sensor sitting in that reservoir tells the controller when to run the compressor and when to coast.<\/p>\n Here is where a lab recirculating chiller stops resembling a rooftop HVAC unit, and where most generic explanations stop being useful.<\/p>\n The refrigerant loop only chills the reservoir. Nothing has happened to your chemistry yet. A second, entirely separate loop \u2014 coolant, pump, hoses, your equipment \u2014 is what actually does the work. The pump has to push fluid out of the reservoir, through hose, through whatever restriction your condenser or reactor jacket presents, and back. Two numbers govern whether it can:<\/p>\n On our sheet, the DLSB-30-30 runs a 20 L\/min pump against 20 m of head through DN15 inlet and outlet connectors<\/a>, and it ships with a 3.8 m circulation hose. The DLSB-10-30 carries the same 20 L\/min and 20 m. Only at the top of the family does the pump step up: 45 L\/min, 25 m of head, and DN20 ports.<\/p>\n Read that again, because it is the single most useful thing on the sheet. Pump capability does not scale smoothly with reservoir size. Two units in this family share a pump. If you are running long hose runs or a tall setup, the pump \u2014 not the compressor \u2014 may be what forces you up a size.<\/p>\n Every unit in this family is listed as a sealed type, -30 \u00b0C to room temperature<\/em>. That word is doing more work than it looks like.<\/p>\n An open bath at -30 \u00b0C is an atmospheric water trap. Room air holds moisture. That moisture condenses and then freezes on any surface below its dew point, which at -30 \u00b0C means every surface in the bath. You get three problems, in this order:<\/p>\n A sealed loop closes the coolant off from room air, so none of that happens. This is the distinction that generic “how a chiller works” pages skip entirely, and it is the one that decides whether a low-temperature bath still hits its rating in year three. If you are shopping across the family, the sealed recirculating chiller range shares this construction across all three sizes<\/a>.<\/p>\n Here is the real parameter table for the three DLSB sizes, straight from the sheet.<\/p>\nWhat the pump side actually does<\/h2>\n
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Why does “sealed” matter below zero?<\/h2>\n
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What the spec sheet tells you, and what it hides<\/h2>\n