【 Weak current College 】 air source heat pump system in domestic central air-conditioning applications (2)---Power By 【 China power house network 】

3. air source unit converter technology

Due to various factors, for the majority of inverter air conditioner is more and more accepted by users. Use of inverter compressor, increased system of adjustable parameters, improved air conditioner part load performance, flexible control of variable capacity instead of stop-and-control, reducing the impact of the system on power grid and the interior temperature fluctuations, from energy-saving and comfort standpoint than constant speed air conditioner has obvious advantages.

Household central air-conditioning with specific usage requirements, usage conditions, the greater the difference in heat load, which requires household energy regulation of central air conditioner and heating load capacity to change the scope of this feature, now the market most air source unit of energy regulation are only available through start stop compressors, when air conditioning heat load is relatively small, chilled water system capacity is low, prone to frequent start stop compressors, compressor start current is large, thus allowing operation power consumption to increase; and after each shutdown of the refrigeration system and high-voltage side of pressure after a period of time to reach a balance, balance high side hot refrigerant and low-voltage side of the refrigerant mixture can also produce unnecessary cooling capacity losses. In addition, opening down too frequently will shorten the service life of the compressor. In recent years, with air conditioning and technological progress, in household central air conditioning products have a variety of energy regulation, application there are more ways: ① refrigeration system uses multiple constant speed (set to lose volume) Compressor Combo; ② refrigeration system with variable speed transmission gas compressors and Compressor Combo; ③ refrigeration systems using frequency compressors and constant speed Compressor Combo; ④ multiple refrigeration system combination. For more of the refrigeration system for combination units, energy regulation capabilities with the system volume, compressor types of different has a big difference, with constant speed (set to lose volume) compressor system can only achieve energy distribution regulation, such as adopting inverter compressor systems with constant speed compressor system combinations you can achieve energy continuously adjustable. Therefore, if the product has a modular structure, the design specifications of the frequency and type of unit, through a variety of combinations, you can generate energy adjustable series products.

Inverter compressor and constant speed compressor combination of frequency unit not only to adapt to the heat load difference for home users, energy regulation range of use, rapid cooling (heat), the system water temperature fluctuation is small, when defrosting water temperature decrease is small, but significant energy efficiency and to achieve continuous bulk units, energy regulation and to increase the service life of the unit, room comfort and noise reduction are good, is the development of domestic central air conditioner is strongly encouraged.

4. water system thermal stability issues

Household air source crew and single cold units of compressor for constant-speed compressor, because the air conditioning system of the water capacity of smaller, will exist chilled water system of thermal stability issues. With constant speed compressors of air conditioning system, a source of household energy regulation generally under indoor temperature changes through start stop compressors. Most household air-conditioning systems are running in a partial load, in part load, the compressor running very short time, the air conditioning system water temperature will reach the set temperature, at which time the compressor downtime; when water system capacity is low, after a very short time,

Air conditioning system water temperature is higher than the set temperature, the compressor must be turned on, causing the compressor frequent start stop, which increases the system power consumption, also affect the life of the host. Furthermore, the water system capacity is low, the winter defrosting time and cause system water temperature drops too large, the formation affect the heating effect, the cold wind blowing. Inverter compressor and constant speed compressor combination of air conditioning system, hosts can automatically matches with indoor load, water system of thermal stability issues not prominent, but water system capacity is too small, at constant speed by frequency compressors and compressor connection of load blind area can have multiple starting and stopping the compressor.

System of water, the smaller capacity, lower the heat stability, on the contrary, the thermal stability of the system, the better. But if the system water capacity is too large, and will cause the energy circulation tank size, when first powered on impact and long-term downtime after cooling (heat). Therefore, the water system design time, you should check whether the water capacity of computing system meet the system requirements for thermal stability. When the system water capacity cannot meet the demands that there should be pumped circulation tank or take more system pipe diameter measures.

5. indoor and outdoor machine layout and design

Household central air conditioning and equipment selection, air-conditioner layout should take full account of the temperature distribution, gas distribution, maintenance, security matters, and should be combined with the building. Air conditioning device settings (indoor, outdoor, balcony, etc.) and building construction (azimuth, equipment reserved channel, etc.) and household room layout (Windows, furniture and location, etc) on the design drawings should be clearly marked. National and local regulations should also be in air conditioning equipment layout and design are strictly enforced. Outdoor unit design must be taken into account its installation location and noise control. General unit installation location to the patency of air, wind speed control for 3 ~ 4m/s, the exhaust is not affected by the barrier, particularly outlet undue barrier above, otherwise it will cause a short circuit, exhaust airflow unit for thermal protection and downtime.

6. system pipe design

Residential central air conditioning system is generally smaller, water system design to simple design issues as follows:

(1) Water Recirculation system

Water system generally uses two control closed circulatory system, comfort requirements particularly high luxury residential use four control. Because the system is small, water pipes are used vary depending on the program.

(2) design and constant flow pump configuration

Household central water air conditioning system cycle, use a small constant flow system. Indoor temperature control can use blower fan coil pipe automatic speed control thermostat or electric three-way valve, it is recommended that the preferred wind up automatic speed control thermostat, by regulating the trend of disk volume of constant room temperature, it is not advisable to use electric 2-way valve (when only a blower coil work by refrigeratorA serious lack of flow will). Because most domestic central air-conditioning system and for intermittent operation while using coefficient is low, the terminal equipment capacity larger than refrigerator, fan-coil is a serious lack of flow and water temperature cannot be stabilized to the set temperature, the design process should take measures to ensure that the flow of fan coil and flows through the fan coil of actual traffic and the most adverse water temperature, air blower plate Tube performance check calculation. [6] water flow control can also be used between fixed and variable flow between mixed mode, in this way, off-host close to the part of the fan coil electric 2-way valve, other fan-coil electric three-way valve, you can save the pressure differential bypass valve, in this manner, it should be noted that 2-way valves and the proportion of direct links. Three-way valve quantity is too small, can cause host due excessively low flow and protect the machine.

(3) a sea of trouble-free design

Circulating water system failure in the entire air-conditioning system fault share is relatively high failure comes mainly from the unit, system design, system installation, etc. In order to improve the reliability of the system, in design and manufacturing units, for all aspects of water system for detailed analysis and strict control is very important. Such as: a. the exhaust system. Household central air conditioning system of water relatively small, a small amount of gas that can cause a loop water break, Frost evaporator or forms of protection, so that the system does not work, so that the system of air time, completely emission is very necessary. To this end, the system is generally installed with automatic discharge valve, but because of the mostly residential central air conditioning built-in pump, sealed expansion water tank, flow protection device, unit of internal water circulation pipes are often more complicated layout seems not very easy, especially easy to form a local saving gas on convex curved, result in the unit's operation process, often because the local gas flow protection arise, this time in product design is absolutely want to avoid. B. additional circulating water and drainage. Residential central air conditioning is an appliance-based products, so that all functions should seek to set auto-completion, the system of internal circulation water added,

You must use an automatic water valve according to the system pressure real-time system water. For system memory water emissions taking even more important, especially for single cold units, in the winter period of non-use, must drain the water within the system, so as not to be too cold for outdoor air temperature freezing system piping. C. water system monitoring and protection. In order to ensure the efficient operation of the unit normal water pipeline should set the appropriate monitoring and protection device. If the unit intake should be set up water treatment equipment and y filter, to waterproof system scaling and plug the unit of heat exchanger; unit for return pipe should be installed on the road and the pressure gauge, thermometer to check the daily operation of the unit and plumbing connections; the Office should set the hose, to reduce the body's vibration on the impact of the pipeline system; to facilitate system debugging and water flow regulation, air conditioning and fan coil pipe shut-off valve to choose a certain effect of closing the valve or the valve.

(4) all-in-one unit and split unit

Air-conditioning host according to the local climate situation to select all-in-one unit or split units, split units to water heat exchanger and the circulating water pump, placed in the indoor unit, indoor bathroom or closet installation on ceiling, in order to prevent freezing during winter. Unit generally comes with expansion tank, water systems, safety valve, automatic water valve, drain valve and so on, the user can do not need to separately install expansion tank, but indoor installation should set aside a certain amount of space to ensure that the unit be able to carry out repair and maintenance.

(5) the built-in pump and water pressure

Household air source unit refrigeration capacity is not large, generally using built-in import circulation pump. Air-conditioning host built-in pump flow rate and head should be in accordance with the unit's cooling capacity and ensure the maximum number of fan coil for normal use to match. Air-circulating water system water pressure, at present there are two methods that set expansion tank and gas pressure expansion tank. A. system set expansion tank. In this way set expansion tank, reliable operation, low cost, conditions should try to use this way. The main problem for many layers of collection apartments or apartment building to address expansion tank Setup location. B. use of gas pressure expansion tank. This method has the advantage of constant pressure is: expansion tank layout flexibility, high impact by location, usually in the unit, reducing the workload of the construction. Its main drawback is that the device is more complex, the price is high, the pressure on the need to adjust, reliability than expansion tank.