Understanding Heat Dynamics in Fish Tanks: Is Your Refrigeration System Ready?
Can an empty space between the hull, deck, and a few bulkheads really affect your refrigeration dynamics? The answer is a resounding yes. While determining the refrigeration required to chill or freeze a ton of fish caught in an hour or a day is straightforward, the often-overlooked factor is how much refrigeration is lost attempting to chill the tank itself. Calculating this can yield surprising results.
The Testing Process: Analyzing Tank Heat Dynamics
To begin, simulate real-world conditions by adding the same amount of water to your tank as you would when chilling fish. You can either flood the tank or introduce just enough water to operate a spray system. If your vessel is equipped with a circulation pump and piping, activate this system for a more precise analysis. Allow a few hours for temperatures to stabilize, then measure the water temperature using a reliable mercury thermometer.
Next, replicate typical vessel operations:
Start the main and auxiliary engines.
Activate all equipment used during travel and fishing.
Untie the mooring lines and take your boat through its paces. Travel for several hours, run the hydraulics, turn on the galley stove, set and haul some gear, and even use devices like hair dryers.
After completing these activities, recheck the tank water temperature. Are you surprised? Water temperatures in fish tanks have been observed to rise by as much as 30 degrees in just 36 hours. What’s causing this heat, and how can it be managed?
Heat Sources to Investigate
Chilling fish involves not only achieving the desired temperature but also maintaining it, which requires less refrigeration capacity once stabilized. However, the heat generated during operations can quickly outpace refrigeration capabilities if left unchecked. Here are some common culprits:
Lack of Insulation or Saturated Insulation
Insufficient or waterlogged insulation significantly increases heat transmission.
Machinery Space Bulkheads
Bulkheads adjoining machinery spaces can conduct heat directly into the tank.
Keel Coolers Below Fish Tanks
Heat from keel coolers located beneath the tank may transfer upward.
Shaft Alley Covers
These can transmit heat from shaft bearings into the tank area.
Cavitating Pumps
Cavitation generates unwanted heat and reduces pump efficiency.
Deck Paint
Non-reflective deck coatings absorb and radiate heat downward.
Refining Your Refrigeration Requirements
Once you’ve identified and addressed these constant heat sources, repeat the temperature analysis procedure to determine the remaining temperature rise that must be accounted for. With this information in hand, you’re ready to consult with IMS specialists. Our team can provide a properly sized and efficient refrigeration system tailored to your vessel’s specific needs.
Don’t let hidden heat dynamics compromise your catch quality. Contact Integrated Marine Systems today for expert advice and industry-leading RSW solutions.