Marine Refrigeration

How does sea cooling work? The main components of DC cooling systems include refrigerant, compressor and condenser, condenser cooling system and plates or plates in the cooling compartment.

The compressor is a closed loop pump coolant through the system and through the evaporator plate in the ice box. The compressor has two sides on the high side or on the discharge side. The discharge side pump the refrigerant under pressure to the condenser. The suction side or the low side and the coolant are inhaled after passing through the evaporator plate to the compressor. Cold plates in the cooling compartment or expansion valves or capillary tubes are provided that isolate the low and high pressure side of the cooling system.

The refrigerant starts as a gas in the compressor. The compressor compresses the refrigerant gas from low to high pressure from 100 to 150 psi. If the pressure rises, the temperature of this temperature rises dramatically. This hot high pressure refrigerant is then fed to a condenser where it is cooled and turned into liquid. The condenser is cooled with air or water. The refrigerant now supplies a cool high-pressure fluid and is fed to the evaporator in the fridge.

The evaporator sheet captures the refrigerant from the condenser, and here it quickly sprinkles and flows back into a gas at a very low temperature. This state of change absorbs a reasonable amount of heat from the evaporator that removes the heat from the insulated cooling box and thus reduces its temperature. The BTU is the measurement of the removed heat. From the evaporator plate, the refrigerant is returned to the bottom of the compressor to restart the process.

Evaporator or support plates

Evaporation plate or support plate at refrigeration refrigeration or freezer compartments. Each type of disc works differently in the boat's fridge and in the heat of the icebox.

Marine Evaporator

The Marine Evaporator is like in household refrigerators. Quite cold (thermostat setting) and many evaporators are able to come to ice with the evaporator plate or inside the evaporator box. Evaporators come in many shapes and sizes; there may be horizontal plates, vertical plates and rolled plates. Evaporators are of constant cycles or short cycles. Most Danfoss marine compressors operate with H134 refrigerant

Thermostat controlled evaporator temperature. Turn to the lower ice box temperature. Evaporative disks are cheaper but require constant resources.

Marine Taps

The disc draws the heat from the fridge. Holders can store iceboxes for a long time.

The main advantage of the support plate over the evaporator is that it needs to be charged 1-2 times a day. This charge may coincide with the ground power supply by running the motor, so the refrigerator does not rely on the battery compartment. When installed in a properly designed system, preservative plates can significantly reduce energy consumption. However, DC support plates are also possible. The support plate is filled with a solution having a freezing point below 23 ° C. As the compressor works, the refrigerant passes through the trays of the trays freezing the support plate solution. The compressor rotates and the support plate is melted and the heat is removed from the box.

Commissioning the Compressor

Compressor power supply is one of the key elements of a ship's cooling system. Cooling is one of the largest energy consumers on board, so the power supply is an important element of the system. The power of marine cooling systems is AC, DC, Shore Power, Engine power and hybrid systems. Hybrids are combinations of 12V and motor drives, or motor and solar power. The whole point looks at the power supply of the fridge to fit the navigation systems of all its vessels into the onboard power supply requirements. If you are running a generator for most of the time, the addition to the AC cooling unit makes sense, but if not, it would be better to use the 12 V, motor or sea power

to use the boat. She drove to the dock for most of the time and made daily trips. Or do you fly and spend a lot of time in the anchor? Finally, Power Boat or Sailing also affects the power supply. Sailing means that the batteries are not charging or there is no current from the engine. Here, a solar cell or wind or towed generator can help to charge your batteries. If you spend time in the dock, the DC system has a lot of time to charge. If you spend time on the drive and the dock and the motorized drive work well with the help of the party.

AC 110 volt marine fridge

These coolers are like home and are usually on larger ships with many ACs. The AC of the marine compressor and the condenser is usually air-cooled.

DC Marine Cooling with Evaporator

One of the cheapest marine cooling systems and the simplest to install a 12 V or DC system. Air cooling is the simplest. The DC system in combination with a thermostatic controlled evaporator plate provides greater flexibility than cooling requirements. Many 12-volt systems use the Danfoss compressor. Due to the increased efficiency of the Danfoss compressor, DC cooling becomes more efficient on board, but is still under power.

For most small vessels, a single 12 V compressor, air-cooled condenser and evaporator, the disk is the cheapest option. The Adler Barbour cold machine is approx. It has been operating for 25 years and provides large cooling for small and medium sized ice boxes.

Shore-powered sea fridge

to keep the ship's ice box at the set temperature when the boat is in the harbor. They offer less power than just the engine drive, but since you are in the dock for a while, this is no problem.

If you are using a support disc and coast systems, keep the disc cool at 12 o'clock from the dock.

Motorized Marine Refrigerator

Behind the engine driven compressor system is the idea that the engine will be used in an hour or so. If there is strong navigation, it makes sense when calculating how much time you spend on the engine when sailing.

If this is the case, a motorized drive can withstand the ice box with a support plate shortly and then it will have 12 extra hours.

The compressor runs directly on the engine. Belt or Direct Compressor, There are two discs and you can add more, plus a separate freezer unit. This creates the support plate's performance and fast cooling. More power than a 110 volt system. Larger systems and multiple disks are possible. Engine driven systems are additional costs and include higher labor costs.

Condenser Cooling

The marine cooling system condenser needs cooling. This cools the refrigerant and becomes liquid. Cooling the condenser in 3 ways:


Air cooling simplifies equipment and does not rely on water or added to hulls. Therefore, the cheapest installation. For smaller units, the air cooler is OK, say, under 4 cu ft or 6 cu ft. The air cooler needs a sufficient amount of re-circulated air to operate. Cooling in the duct and adding ambient temperature removes heat from the condenser. The temperature inside the cabinet has enough capacity to disperse this heat.

Water Cooled Condenser

Water Cooled Compressors work better at higher ambient temperatures and are more efficient and 30% more efficient. Water cooling can be the best and is better for larger installations, especially if the freezer is concerned. The hull and pump must pass through the water cooling to allow the water to reach the condenser. The most efficient way to cool down the condenser

Star Cooling Condenser

The spooler or spine condenser does not require a rolling structure and will not be clogged. The spooler is a 3 "x 7" bronze plate that strengthens the condenser heat exchanger on the outer surface of the hull. The bronze plates are directly connected to the compressor, which is the only moving part of the system. The cooler can be used for a 15-inch refrigerator or 5-ft freezer. Since all the heat is transferred to the water on the outside of the vessel, the interior does not warm up. Since it does not work with a water pump, there is never a pump or filter available and it is best to almost listen.

Refrigerant Compressor and Disc Combination

Before choosing the size of the marine fridge, we need to understand what factors are in keeping the cool box cool. Especially the size of the box, insulation and cooling water temperature, the number of decks and the temperature to set the disks. , the larger the box, the more heat withdrawal is needed. In a larger box several heat exchanger devices are required. After the basic size, there are things like Opening the Front or the Top Opening. The first opening allows cold air to pass quickly, but allows you to reach the bottom of the box. Drains, if there was a canal for you, plug in ice box. It does not have to drain the water from the icebox and it only lets cold air and penetrates. Seals, mandatory. A trick is to identify if there are gaps in the seal to place a paper between the lid or the door and the cabinet and close it. Pull up the paper and feel some pull when the seals are properly sealed. It turns out there is a gap. You can get new or better sealing material.


Typical insulation for a refrigerator or freezer foam insulation such as Dow Blue board. The recommendation refers to 3-4 inches of cooling and 4-6 inches of medium sized freezers. The foam has an R value of 5 / inch thickness, R is a thermal unit. This means that the thermal units represent 3-4 inches of 15-20R for the refrigeration unit and 20-30 on the freezer.

There are Vacuum Panel Insulation Manufacturers. In the Glacier Bay, the R-50 per inch Barrier Ultra-R Super Insulation provides many insulation without having to pick up valuable amounts. These panels are vacuum panels and have closed the work. It is very important not to drill or puncture these panels. These panels are custom made, so the manufacturer needs to be brought into the box, accurate sizes for copper tube tubes. These are built into the panels

Water Temperature

Tropical temperatures are much warmer than the Northern Climate. Water temperature increases at 2% of the corresponding BTU at each step. If the Atlantic coasts are on the east coast of the United States, there are some cool sea water, but then you can move to the Caribbean, and you can freeze the cooling system.

Plate Thermostat

The temperature of the evaporator plate is set by the thermostat. Dial the box temperature and the system needs to work harder

Number of people on board

More people mean that the box opens more, more people add ambient temperature

How big is the cooling system?

To calculate the size of a freezer or sea freezer, you must begin to estimate the box's BTU requirements. For estimating BTUs, a simple rule is based on the box volume

These BTU estimates are based on these assumptions

– Insulation has no leakage value R

– The 80's tropical water temperature in the middle of the years

– on board 2 persons, additional 1000 BTUs per day

opening with 15 BTU / inch doors

BTU estimate cooling volume;

Daily heat load of a refrigerator; 600 BTU per cu. ft

Freezing daily heat load; 1200 BTU per cu. ft

It can be seen how this works on the 4-inch cooling system using the above formula

4 cu. ft. time 600 = 2400 BTU

Two additional people on board = 2000 BTU

Daily total required = 4,400 BTU


Add this number to the compressor capabilities, then calculate the amplifiers needed to power the system and then perform the battery bank capability. Start with the 4,400 BTU format above. The Adler Barbour Cold Machine has a Danfoss BD50 compressor rated power of 650BTU / hour based on the 25F evaporator temperature.

This far exceeds 4,400 HUF / day for a 4-inch refrigerator, 3 is power. The Danfoss DB35 is easy to go


To calculate the number of amplifiers that will be pulled by the BTUs, assuming 5 BTU / watt / used energy. BTU / 5 / V is said to be 4400 BTUS and 12, 4,400 / 5/12 = 74 amperes per day.

Battery Bank

should be 1/4 of the house's bank capacity. So the above 74 amp hours are required to multiply by 4 to get the recommended home battery capacity = 296 amp hours.

and cold drinks. 12 volt refrigeration units are becoming more popular with technological advances. The higher compressor efficiency and the evaporation technology allow 12 years of cooling for the smallest vessels.

Source by Mike Hobson

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