【 Weak current College 】 heat pump principle and application of air-cooled heat pump selection

Heat pump units due to its energy-saving, environmental protection and the advantages of cold and warm with available, currently in the country. This is a collection in various newspapers and magazines across the country, annual data collection and on the application of heat pump technology and the paper altogether 207 article. In this Symposium as a for all teachers and students. Summary of the problem are as follows:

Air source (air-cooled) heat pump current products mainly household heat pump air conditioner, commercial modular heat pump air conditioner and heat pump chiller. Heat pump air conditioner has been accounted for sales of 40 ~ 50% of annual capacity to 400 million units. Heat pump chiller start since the early 1990s, in the hot summer and cold winter region has been widely applied, according to incomplete statistics, the region part of the city central air conditioner cold heat source heat pump chiller has accounted for 20 ~ 30%, and the application continues to expand and move to this trend.

1. with regard to the evaluation of air-source heat energy consumption

In order to evaluate and compare heat pump unit and other energy NUAN, approximately 30 papers related to this issue. Describes applies to heat pump unit energy consumption analysis: theory and software, according to the air conditioning cooling load, outdoor dry-bulb temperature, heat pump water temperature, using parameters such as temperature, frequency method for heat-pump cooling energy consumption throughout the year. In the winter for the heat pump can be time consuming, apart from considering air conditioning heat load, heat pump water temperature, outdoor dry-bulb temperature, relative humidity of the outside (i.e., temperature and humidity frequency) to take into account the performance of the heat pump, software engineering, and the actual consumption of energy has a better fit for the energy evaluation provides a way.

2, air-source heat pump unit selection

The current design choice of air-cooled heat pump, often based on the calculated cooling load and thermal load, consider using coefficient and cold (hot) capacity loss coefficient, press unit nameplate calibration value Select line numbers. Because air source heat pump unit of production volume of cold (heat) with outdoor parameter changes, the method could result in the unit selection too large, wastage, or selected too small, so that the cooling (heat) levels are low, not to use requirements. To this end suggests using air conditioning hourly cooling load and thermal load and the heat pump for heating and cooling capacities of hourly change curve control selection, will be more satisfied with the results.

3. heat pump winter defrosting

Air-source heat pump heating runs, the biggest problem is when the outdoor temperature is low, outdoor side heat exchanger fin surface will frosting, (need for defrosting measures). Excerpt from the documentary, the second year of field track testing, the result is loss of defrosting or about heat pumps total energy loss 10.2% due to the defrost control methods, some 27% of defrosting function is in fin surface frosting not serious, no need to defrost enter defrosting cycle. Some methods currently used, more or less problems, such as extra defrosting actions, or need to defrost time rather than signals and other ills. The best literature of defrosting time control and maximum average heating control defrost, theoretically very innovative, but more difficult to implement.