Ancor Marine Electrical Nickel Plated
Apr 23, 2011 Brass Instruments
Posted by
Mario Carey
|
How does Marine refrigeration work? The major parts of a DC refrigeration scheme include the refrigerant, a compressor, and a condenser, a cooling scheme for condenser, and a plate or plates inside the refrigeration box. The compressor is share of a closed loop pumping refrigerant through the scheme and through the evaporator plate in the ice box. The compressor has two sides the High side or discharge side. The discharge side pumps refrigerant under pressure to the condenser. The suction side or low side and sucks refrigerant after it passes thru the evaporator plate back to the compressor. The cold plates in the fridge space have either elaboration valves or capillary tube that distinguished the low and high pressure sides of the refrigeration system. The refrigerant in the compressor starts as a gas. The compressor compresses the refrigerant gas, from low pressure to high pressure amidst 100-150 psi. When the pressure is increased like this it is temperature is raised dramatically. This hot high pressure refrigerant is then fed to a condenser, where it is cooled and turned into a liquid. The condenser is cooled by either air or water. The refrigerant is now a cool high pressure liquid and is fed to an evaporator plate inside the boats refrigerator box. The evaporator plate takes the refrigerant from the condenser and here it boils quickly & evaporates back to a gas, at a very low temperature. This modify of state absorbs immense amounts of sensible heat from the evaporator which in turn removes heat from the insulated refrigeration box, thereby letting down it is temperature. The BTU is the measurement of heat removed. From the evaporator plate the refrigerant is returned to the low side of the compressor, to get started the routine again. Evaporator or Holding Plates Marine refrigeration systems use either an evaporator plate or a keeping plate in the boats refrigeration space or freezer space. Each type of plate works differently in drawing heat from the boats refrigerator and ice box space. Marine Evaporator Marine Evaporators are just like the ones found in household refrigerators. They may get rather cold (thermostat setting) and a heap of evaporators have the capacity to make ice next to the evaporator plate or inside the evaporator box. Evaporators come in assorted shapes and sizes; they may be horizontal plate’s vertical plates and rolled plates. Evaporators are continuous cycling, or short cycle. Most use a Danfoss marine compressor with H134 refrigerant. Thermostat controlled evaporator temperature. Turn to lower ice box temperature. Evaporator plates are less expensive, but need Constant power supply. Marine Holding plates Marine Refrigerator Holding Plates act like huge blocks of ice and the cold temperature of the keeping plate sucks heat out of the boats refrigeration box. Holding plates may keep ice boxes cold for long periods. The main vantage of a keeping plate over an evaporator is that they only need to be recharged 1 or 2 times per day. This charging may coincide with attaching to shore power, running the engine and so the refrigerator does not rely on the battery bank. When integrated into a the right way designed system, holdover plates may significantly reduce intermediate energy consumption. However DC keeping plates are also possible. The keeping plate is filled with a solution that has a freezing point under 23 degrees F. As the compressor runs, the refrigerant passes through the keeping Plates coil, freezing the keeping plate solution. The compressor turns of and as the keeping plate thaws out, heat is got rid of from the box. Powering the Compressor The power supply to the compressor is one of the key constituents of the boats refrigeration system. Refrigeration is one of the greatest energy buyers onboard, so the power supply is an necessary factor of the system. Power furnishes to marine refrigeration systems include AC, DC, Shore Power, Engine power, and hybrid systems. Hybrids are combinings of say 12 volt and engine drive, or engine and shore power. The whole point in looking at power supply to your boats refrigerator is to couple it into onboard power necessaries for all your boats marine systems. If you run a generator much of the time then adding on an AC refrigeration unit may make sense, but unless you do, you would be better at looking at 12 V, engine or shore power. Power may be decisive on how you use your boat. Are you tied up at a dock for much of the time and take days trips. Or do you cruise and spend big amounts of time at anchor. Finally are you Powerboating or Sailing will likewise influence power supply. Sailing means no charging of batteries or power from the engine. Here a solar panel or wind or towed generator may support replenish batteries. If you spend time at the dock, a DC scheme has a great deal of time to recharge on shore power. If you spend time motoring and at the dock and engine drive with shore aid works well. AC 110 volt marine refrigeration These drop in refrigerators are like the one in your home and are commonly seen on larges boats with an abundance of AC power and space. The AC powers the marine compressor, and the condenser is distinctively air cooled. A dependable AC supply is necessitated in the form of a generator. DC marine refrigeration with Evaporator plate One of the most inexpensive marine refrigeration system and easiest to install is the 12 v or DC system. Air cooling is the simplest. The DC scheme combined with an evaporator plate that is thermostatically controlled gives flexibleness over cooling requirements. Many 12 volt systems use the Danfoss compressor. With the increased efficacy of the Danfoss compressor, DC refrigeration onboard is getting more efficient, but is still power hungry. For most boats with a little box, a single 12V compressor, air cooled condenser, with evaporator type plate will be when it comes to the most inexpensive option. The Adler Barbour Cold Machine has been around for around 25 years and provides great refrigeration for little to medium size ice boxes. Shore powered marine refrigeration Shore powered systems are made to maintain the boat’s ice box at set temperature when the boat is at the dock. They offer less power than direct from an engine drive but since you will be at the dock for a while that is not an issue. If you use a keeping plate and shore powered scheme you may keep the plate cool while away from the dock for 12 hours or so. Engine powered marine refrigeration The idea behind an engine driven compressor system is that the engine gets employed anyway for at lest an hour or so. If you are Powerboating this makes sense, if you are sailing calculate how much time you use the engine. If this is the case an engine drive with a keeping plate may draw down the ice box in a short amount of time and after that it may be left for 12 plus hours. The compressor is run directly off the engine. Belt driven or direct compressor, There are two plates and you may add more, plus ad a discerned freezer unit. This brings about much power and fast cooling of the keeping plate. More power than a 110 volt system. Larger schemes and multiple plates are possible. Engine driven schemes cost more and likewise implicate a labor higher cost Condenser Cooling The marine refrigeration systems condenser needs cooling. This is how the refrigerant gets cooled and turned into a liquid. There are 3 ways to cool the condenser; Air Cooled Air cooling simplifies installation plus it does not rely on water or adding by way of hulls. It is hence the most inexpensive installation. For littler units air cooling is OK, say 4 cu ft or beneath 6 cu ft you will get adequate performance. The air cooling unit needs a sufficient supply of re-circulated air for it to work. Ducting and space around the unit will aid this. When you cool by air flow you remove heat from the condenser and ad it to the ambient temperature. The temperature inside of the cabin only has sufficient capacity to disperse this heat. Water cooled Condenser Water cooled compressors will work better in higher ambient temperatures and are more effective and may be 30% more efficient. Water cooling may be best and is better for larger installs exceptionally if freezer is concerned. Water cooling needs a thru hull and a pump to get the water to the condenser. The most effective way to cool the condenser Keel cooler Condenser The keel cooler or keel condenser requires no thru hull fitting and will not be subject to clogging. The keel cooler is a 3″ x 7″ bronze plate that mounts on the outside of the hull and it is the condenser heat exchanger. The bronze plates are connected direct to the compressor which is the only moving percentage in the system. The Keel Cooler is for a box up to a 15 cu ft refrigerator or 5 cu ft freezer. Since all the heat is passed into the water outside the boat it will does not heat up the interior. Since it works without a water pump there is never a pump or strainer to maintain and best of all it is closely silent in operation. Refrigeration Compressor & plate Combination Before we pick a size of marine refrigerator we need to grasp what components are involved in keeping the refrigeration box cool. They are mainly box size, insulation and cooling water temperature, number of persons aboard and the temperature you are setting the plates for. Refrigerator Box Volume This is obvious, the more prominent the box the more heat remotion is necessary. A more spectacular box will need more BTUs of heat removal. After this basic size issue we have things like, Front opening or top opening. Front opening lets cold air out quickly but does concede you to get to the bottom of the box. Drains, if you had a drain for you ice box plug it. You will not need to drain water out of the ice box and this will only let cold air out and heat in. Gaskets, these are a will have to and will have to be the right way sealed. A trick to tell apart if there are gaps in the gasket is to put a piece of paper in among the lid or door and the cabinet and close it. Pull on the paper and you ought to feel some drag if the gaskets are sealing properly. It comes out without apparent effort there is a gap. Get new or better gasket material. Insulation Typical insulation to a fridge or freezer is foam insulation like Dow Blue board. The recommendation is for 3-4 inches for refrigeration and 4-6 inches for freezer for medium sized boxes. Foam has an R value of 5 per inch thickness, R being a thermal unit. This means in terms of thermal units 3-4 inches represents 15-20R value for the refrigeration unit, and 20-30 for the freezer. There are makers of vacuum panel thermal insulation. The Glacier bay Barrier Ultra-R super-insulation at R-50 per inch provides lots of insulation without taking up priceless volume. These panels are vacuum panels and are sealed to work. It is very crucial that you do not drill through or puncture these panels. These panels are habit made, so you would need to provide the manufacturer, precise sizes with locatings for copper plate tubes to enter the box. These are built into the panels. Water temperature In the tropics water temperature is a lot warmer then northern climates. For each degree water temperature increments a sameness 2 % increase in required BTU. If you are in the Atlantic portions of the east coast US, you have galore cool sea water temps, but of you then cruise down to the Caribbean you may strain your refrigeration system. Plate Thermostat The evaporator plate temperature is set by the thermostat. Dial the box temperature down and the scheme will have to work harder. Number of people aboard More humans means the box gets opened more and the heat build up from more humans adds to the ambient temperature. How huge a Refrigeration System is required? To calculate how huge a refrigeration or marine freezing unit required, you will need to begin with an estimation of the BTU necessaries of the box. A simple rule of thumb for estimating the BTUs is based on the box volume. These BTU estimations are based on these assumptions; - Insulation has an R value of 30 no leaks. BTU estimate on refrigeration volume; Refrigerator daily heat load; 600 Btu per cu. ft. Freezer each day heat load; 1200 Btu per cu. ft Lets look at how this works for the 4 cu ft refrigeration system, using the above formula 4 cu. ft. times 600 = 2,400 Btu. Two further and added humans on board = 2,000 Btu. Total required per day = 4,400 Btu Choosing 12 volt unit with Evaporator Match this number to the compressor capabilities, and then calculate amps necessitated to power the system, and then work on the battery bank capability. Start by using the 4,400 BTU form the above example. The Adler Barbour Cold Machine uses the Danfoss BD50 Compressor is ranked at 650BTU / hr based on 25F evaporator temp. This is well above the 4,400/day we need for the 4 cu ft fridge, using only with regards to 1/3 of the power. We could effortlessly go down the Danfoss DB35. Amps To calculate how a lot of amps the scheme will draw we commence by converting BTUs to amps with this formula, using an assumption of 5 BTUs per watt hr of energy used. BTU/5/volts. so say we have 4400 BTUS and 12 volts, 4,400/5/12=74 amp hours/day. Battery Bank The Amps necessitated to power the compressor will have to be 1/4 of the capacity of the house bank. So for the above 74 amp hours necessitated multiply by 4 to get commended house battery capacity = 296 amp hrs Conclusion These days being on the water means keeping feed and drinks cold. 12 volt refrigeration units are getting more popular with technical advances. Greater compressor efficacy and evaporator engineering science brings 12 volt cooling to the smallest of boats. |
Misleading addTags: boat cooler, boat refrigeration, boat refrigerator, marine refrigeration, marine refrigerator
Leave a Reply
You must be logged in to post a comment.