On the On-Off Operation in a Reciprocating Compressor Refrigeration System with Capillary

Abstract

wang Jun Wu Yezheng Department of Power Machinery Engineering Xi'an Jiaotong University Xi'an, Shaanxi, China In some small refrigerating and air-conditioning equipment with capillary tube, the compressor is started up and shut down frequently. After shut-down the pressures in condenser and evaporator are equilibrium due to the migration of refrigerant from condenser to evaporator. When the compressor is restarted, there is a time lag to build up again the required pressures in the condenser and evaporator to the operating condition. Since the migration during off op~ration leads to more power input in restarting period for the small refrigerating equipment with the capillary, it is necessary to improve the refrigerating equipment by fully understanding the on-off operation characteristics. We have investigated the on-off operation in a sealed reciprocating compressor refrigerating equipment (3.48 kw). Pressure and temperature on either side of the heat exchangers during on-off operation are measured, and the power input after compressor startup are measured too. The effect of migration during off operation on the pressure, temperature and power input has been studied. The main factors which affect the energy conversion have been analyzed. The experimental studies indicate that the prevention of refrigerant migration during off operation could reduce the power input by 4% and the peak value of power input by 9.4%. Concurrently, the cooling capacity can be increased as well as the evaporating temperature and pressure reaches the steady operating condition faster. A mathematical model of the refrigerating system in off operation is developed. The exergy losses resulted from refrigerant migration during off operation is calculated, which is the minimum value of energy to be saved by preventing the refrigerant migration during off operation. FONCT WNNEMENT PAR TOUT OU RIEN D' UN SYSTEME F'lUGORIFIQUE A COMPHESSEUR ALTEHNATIF ET 'rUl3E CAPIJ"LAIRE. R~SUME Dans les petltes installations frigorifiques et de conditionnement d'air ~ tube capillaire, le cornpresseur d~marre et s'arrete frequemrnent. Apres ar~©t, les pressions du condenseur et de l'evaporateur sont en ~quilibre par suite du d~placernent du frigorigenc du condenseur vers l'evaporateur. Lorsque le compresseur redemarre, il y a un temps de latence avant de reconstituer les pressions necessaires du condenseur et de l'&vaporateur pour atteindre le regime de fonc·tionnement. r.a migration du frigorigene lors de l'arre~ exigeant plus d'energ1e au red~marrage pour les petits appareils frigorifiques ! tube capilla1re, il faut ameliorer le materiel frigorifique en comprenant bien les caracteristiques du fonct1onnement par tout ou rien. Les auteurs ant ~tudie le foncti.onnement par tout ou rien d'une installation frigorifique a compresseur alternatif herm~­ tique (3,48 KW). La pression et la temperature de chaque cote des echangeurs de chaleur au cours du fonctionnement par tout ou rien sont mesurees ainsi que la consornmation d'energie apres demarrage du compresseur. L'influence de la migration du frigorigene au cours de l'arr©t sur la pression, la lemperature et la consomrnation d'energie a ~te etudiee. Les principaux £acteurs agissant sur la transformation de l'~nergie ant ete analyses. Les etudes experimentales indiquent

Cite this paper

@inproceedings{Jun2014OnTO, title={On the On-Off Operation in a Reciprocating Compressor Refrigeration System with Capillary}, author={Wu Ya Jun and W. Yezheng}, year={2014} }