【 Weak current College 】 heat pump system design-time considerations---Power By 【 China power house network 】

1. heat pump system and economic operation of basic requirements:

1, the fullest possible use temperature high heat.

2, the heat and the temperature difference between the actual htm.

3. the heat source should meet the following requirements:

--In the highest possible under heating temperature of the heat.

--Use of heat required to increase the fees low.

--Whether in chemistry or physics, heat transfer equipment do not have a negative impact.

--Heat conditions change, better fit.

--Transportation equipment such as fans, pumps, power consumption as low as possible.

2. heat pump system compressor should meet the following requirements:

1, for air-source heat pumps, tz =-35 ~ + 65oC 15oC and tl ≤ within run correctly; the compression ratio as high as 9, still have satisfactory efficiency; at the same time, there should not be excessive overheating temperature.

2 inhalation steam is too hot and not saturated State, the compressor is not affected by the gas quality.

3. can work under pressure of rapid change, do not produce oil foam; oil should return the crankcase with steam, and tank equipped with immersion heater.

4. There should be a good, reliable over-temperature, overpressure protection device. Trouble-free operation time in 25000h above.

5, the larger the heat pump, should be equipped with smooth without loss of energy of the modem.

6, compressor equipped with motor, with flat efficiency curve.

The above requirements, made the following recommendations:

Heating capacity Q = 0.5-500KW, special use.
Heat quantity Q ＞ 500KW, centrifugal.

III. refrigerant flow control

To use thermostatic expansion valve is appropriate and should be a "balancing holes" to remain with inlet pressure changes, and be able to pressure difference smaller cases correctly.

IV. economic judgement

For certain properties of the heat pump system, the application under the following conditions, usually considered to be the economy:

There is a kind of like the good heat source as groundwater.
Each year at full load operating time of no less than 2000h.
COP value > 3
In the summer cooling base for heating loop that does not require additional energy.
Have already been used in refrigeration equipment, such as a cold store, skating rink, supermarkets, etc.
There is heat available. Interior of a older waste heat, possibly in the ambient temperature is below zero with internal heat heating buildings, such as the Department store, cinema, computer room, etc.

Conversely, if the heat pump, its economy would not be affirmed:
Only used for heating.
COP＜3。
Heat pump capacity larger than heating load.