IMPACT OF CHANGING HVAC VALVES TO PIBCVs ON ENERGY EFFICIENCY, EMISSIONS AND SHIP CONSTRUCTION COSTS

摘要

Heating, ventilating and air-conditioning can account for 30% of energy consumption, especially on passenger cruise ships. Large pumps distribute centrally chilled water around a ship via pipes to cabin "fan coils" and "air handling units" (heat exchangers), where the water absorbs heat from the rooms. Most marine vessels still use conventional distribution designs, which operate at higher pump speeds. The pumping is expensive and unnecessary and chiller efficiency is much reduced due to low delta-T syndrome. The pressure in the system must be hydronically balanced to ensure that the flow of chilled water is sufficient over the length of the ship and all distribution systems must be balanced at design flow, i.e. 100%. However, cooling and heating load vary with the weather and user demand. For 80% of time cooling demand is less than 25% and conventional manual systems cannot compensate, keeping costs closer to 100%. The "Pressure Independent Balancing & Control Valve" is a recent innovation, combining "automatic balancing" with a "control valve" and a "pressure controller" in one housing. It has revolutionised building design worldwide. Not only does it enable variable demand to be matched by variable supply, saving energy, it makes system design easier, reduces commissioning time and reduces the number of valves required. All while improving passenger comfort. By reducing required pump speed and preventing low delta-T syndrome, the Pressure Independent Balancing and Control Valve can save 25-30% of HVAC energy costs, equating to about US$1million yearly at today's oil prices for a large modern cruise ship.