Condenser or chiller — the same shell, opposite duties
In a condenser, ammonia vapour condenses on the shell side while cooling water passes through the tubes. In a chiller, ammonia evaporates and the tubes carry the fluid being cooled. Same geometry, opposite direction of heat flow, and quite different selection criteria.
You need a condenser when the plant has to reject heat and water is available. You need a chiller when the load is not a cold room but a process — a pasteuriser, a jacketed tank, a distributed glycol loop — where you are cooling a fluid rather than air.
Plenty of plants use both: a shell and tube condenser rejecting heat from the plant room, and a shell and tube chiller producing chilled water or glycol for the process side.
Pass design and why it matters
Pass count sets how many times the tube-side fluid traverses the shell before leaving. More passes mean higher velocity, better heat transfer and a smaller unit — at the cost of higher pumping pressure drop.
Two-pass suits high flow with a small temperature rise. Eight-pass suits low flow with a large rise. Choosing on unit price rather than on the actual flow available is how plants end up with a correctly sized exchanger that never reaches its rated duty, because the pump cannot deliver against the pressure drop.
We offer 2, 4, 6 and 8 pass designs and select against your available flow and pump head, not against a catalogue default.
Water quality decides tube material
Carbon steel tube is standard and appropriate for closed circuits and clean cooling water. Stainless steel is worth the difference on open cooling tower circuits with high dissolved solids, on borewell water with unpredictable chemistry, and on any brine circuit where chloride content will attack carbon steel.
This is the decision most often made on price and most often regretted. Retubing a condenser is far more expensive than specifying the right tube once, and the failure shows up as a leak between circuits — cooling water into the ammonia charge, which contaminates the whole plant.
The same reasoning applies to the water side generally: scale on the tube surface raises condensing temperature, and every degree of condensing temperature costs roughly 2 to 3% in compressor power. A treated water circuit protects the exchanger and the electricity bill together.
Water-cooled against evaporative
Shell and tube condensers need a cooling water source — a tower, a process return, or once-through water where that is permitted. Evaporative condensers reject heat directly to the air using a much smaller volume of water, and generally give a lower condensing temperature for the same ambient.
Choose shell and tube when you already have a water circuit, when the plant room is indoors with no route to atmosphere, when water chemistry is controlled, or when you need the most compact footprint. Choose evaporative when water is scarce or expensive and you have the space and access to site the unit outdoors.
We build both, and on projects where either would work we will tell you which we would specify and why.
Cleaning and service access
Shell and tube earns its keep over a long service life, and that depends on being able to clean it. Removable end covers give access to the tube sheet for mechanical cleaning, and the horizontal layout means a bundle can be pulled without dismantling surrounding pipework — provided the pull space was allowed for at layout stage.
Leave that space out of the plant room drawing and you convert a routine clean into a shutdown. It is worth confirming on the general arrangement before the foundations are poured.
Applications
Cold storage, food processing, dairy, ice plants, breweries and beverage, chemical and process industries — anywhere an ammonia plant meets a water or glycol circuit. The chiller range covers water, brine, glycol and process cooling duties; the condenser range covers water-cooled, horizontal and stainless tube variants.
