Chiller Performance — Clipper Stad Amsterdam

What's going on

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Latest reading

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LP suction bar g

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HP discharge bar g

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Cond. approach °C

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Subcooling °C

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CHW ΔT °C

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CHW supply °C

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Freeze margin bar

Condensing approach

Condenser condition. Flat & low is good — 16 °C means clean.

LP suction

Suction & freeze margin — keep above 4.5 bar g.

HP discharge

High side. Rises with sea temperature; fine while approach stays low.

CHW supply

Delivered temperature against the 10 °C setpoint.

Sea-water inlet

The main driver of high-side pressure.

Condensing approach — clean limit 16 °C

Approach = saturated condensing temp − sea-water outlet. The cleanest measure of how well the condenser sheds heat, with sea temperature taken out. Flat and low is healthy; a sustained climb toward 16 °C is fouling.

Because it subtracts sea temperature, approach isolates the condenser's own condition — a hot day raises HP but should not raise approach. Clean the sea-water side once approach holds above 16 °C. R449A's ~5 K glide gives the number a ±2.5 °C band, so trust a sustained trend over any single point.

Approach as a gap — sat. cond. temp vs SW outlet

The shaded band is the gap between saturated condensing temp (top) and sea-water outlet (bottom) — that gap is the approach.

A band that rises and falls with sea temperature while staying the same thickness is healthy. A band that thickens over time — condensing temp pulling away from the sea water — is the condenser struggling to reject heat, i.e. fouling.

Sea water — condenser in & out

Sea-water temperature entering and leaving the condenser. The spread between them is how much heat the seawater is carrying away.

In and out should rise and fall together with sea temperature. A healthy spread (SW ΔT) that stays well above the pump's minimum flow shows sea-water flow is not the limitation — the plant is heat-rejection limited, not flow limited.

LP suction — freeze line 4.5 bar g

Low-side suction pressure. It sets evaporator temperature and the freeze margin. Below 4.5 bar g the plate evaporator is at freezing risk.

Suction naturally dips in the early morning as the load drops. If LP sits near or below 4.5 bar g, raise the CHW setpoint — that lifts suction and restores the margin above the plate-evaporator freeze threshold.

Subcooling — watch line 4 °C

Degrees of subcooling at the liquid line. A few degrees confirms a solid liquid seal and adequate charge.

Sustained subcooling below 4 °C is worth investigating for charge; a single low reading is not. Once-daily sampling is enough — it doesn't need logging every reading.

Sea-water ΔT

Temperature rise of the sea water across the condenser — the heat actually being rejected overboard.

A steady ΔT well above the sea-water pump's minimum flow confirms flow is healthy. If ΔT were collapsing you'd suspect a flow or pump problem; steady ΔT points the diagnosis at the heat-transfer surface (fouling) instead.

CHW supply — setpoint 10 °C

Chilled-water supply temperature — what the plant actually delivers. It should sit near 10 °C.

Drifting above 10 °C on hot afternoons is the plant reaching its heat-rejection capacity limit for that load — not a fault, and not a flow problem (running both CHW pumps doesn't change it). It recovers to setpoint as sea temperature falls.

CHW ΔT — load side

Chilled-water return minus supply — the load the ship puts on the plant. It sits flat around 2–2.6 °C.

This flat ΔT is a load-side characteristic, not a chiller fault — do not read it as circuit degradation. It's partly an artefact of the compressor never holding full load long enough to build a wider differential.

Glossary & thresholds

Condensing approach: Saturated condensing temp − sea-water outlet. How hard the condenser has to work above sea temperature. Watch 14 °C · clean 16 °C.
Saturated condensing temp: The condensing temperature implied by HP, read off the corrected Honeywell R449A high-side table.
Subcooling: Saturated condensing temp − liquid-line temperature. Confirms a solid liquid seal. Watch below 4 °C.
LP suction / freeze margin: Low-side pressure. Sets evaporator temperature. Freeze line 4.5 bar g; raise CHW setpoint below it.
HP discharge: High-side pressure. Tracks sea temperature — a high HP on a hot day is normal while approach stays low.
CHW supply: Chilled-water temperature delivered to the ship. Setpoint 10 °C.
CHW ΔT: Return − supply. The load presented to the plant. Flat 2–2.6 °C here is load-side, not a fault.
Sea-water ΔT: Rise across the condenser — heat rejected overboard. Steady ΔT = flow is fine.
Zeotropic glide: R449A boils/condenses over a ~5 K range, so condensing temp is a mean value — differences under ~2.5 °C are noise.

Approach vs sea-water inlet — the fouling test

Each dot is one reading: sea-water inlet (x) against approach (y). A clean condenser holds a flat low band whatever the inlet temperature.

This test removes sea temperature from the picture. If approach stays low as inlet temperature climbs left to right, the condenser is clean. A band that sits higher across all inlet temperatures is fouling — regardless of how warm the sea is.

HP vs sea-water inlet — independent check

Sea-water inlet (x) against HP (y). Healthy, this is a tight rising line — HP simply following sea temperature.

If this line lifts over weeks at the same inlet temperature, that's fouling confirming itself independently of the approach calculation — a useful cross-check that doesn't rely on the P-T table.

R449A high-side P-T reference — bar g → sat. cond. °C

bar g	°C	bar g	°C	bar g	°C

Corrected Honeywell basis (45 °C ≈ 19 bar g). Mean saturated condensing temperature; R449A glide ~5 K gives ±~2.5 °C. High side only — this is what the approach calculation uses.

Condensing approach calculator

HP discharge pressure (bar g) Sea-water outlet temperature (°C)

Saturated condensing temp: —

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Enter HP and SW outlet.

Approach = saturated condensing temp (from HP) − sea-water outlet. Same method as the live sheet, so the number matches the log to the decimal.