The existing researches of stepless capacity regulation system by depressing the suction valve for reciprocation compressor always adopt hypothesis that the compressor valves are open or close instantaneously, the valve dynamic has not been taken account into thermal cycle computation, the influence of capacity regulation system on suction valves dynamic performance and cylinder thermal cycle operation has not been considered. This paper focuses on theoretical and experimental analysis of the valve dynamic and thermal cycle for reciprocating compressor in the situation of stepless capacity regulation. The valve dynamics equation, gas forces for normal and back flow, and the cylinder pressure varying with suction valve unloader moment during compression thermal cycle are discussed. A new valve dynamic model based on L-K real gas state equation for reciprocating compressor is first deduced to reduce the calculation errors induced by the ideal gas state equation. The variations of valve dynamic and cylinder pressure during part of compression stroke are calculated numerically. The calculation results reveal the non-normal thermal cycle and operation condition of compressor in stepless capacity regulation situation. The numerical simulation results of the valve dynamic and thermal cycle parameters are also verified by the stepless capacity regulation experiments in the type of 3L-10/8 reciprocating compressor. The experimental results agree with the numerical simulation results, which show that the theoretical models proposed are effective and high-precision. The proposed theoretical models build the theoretical foundation to design the real stepless capacity regulation system.
Background:Canthariasis is a disease of humans caused by the infestation of beetle larvae.It is the second important insectal disease after myiasis.Several species of beetles are reported to cause the disease in gastrointestinal tract,urogenital system,nasal sinuses,ears and faces of mammals.The cigarette beetle Lasioderma serricorne is a widespread and destructive pest that usually feeds on tobacco,tea,beans,cereal grains,and animal and plant specimen.While there was no previous evidence of human infestation by this worm,we report the first case of L.serricorne infestation in a baby girl in China.Case presentation:Here the case,an eight-month-old baby girl with irritable feeling,rubbing eyes,history of contact with mud and eating oranges twice during five days before attendance,and having“worms”in her stool was admitted to the First Affiliated Hospital of Sun Yat-sen University,Guangzhou,China.The clinical examination revealed that the pulse rate,blood pressure and temperature were regular,and the examination of the head,neck,and chest were unremarkable.The stool specimens containing“worms”were sent to the Department of Parasitology,Zhongshan School of Medicine,Sun Yat-sen University.The worms were recovered,studied morphologically using naked eyes and anatomical lens,PCR analyzed targeting cytochrome oxidase subunit 1(COX1)and 18S rRNA genes,examined by sequence analyses of the PCR products and finally classified by phylogenetic analysis to identify their species.Based on the findings,the worms were diagnosed as the larvae of L.serricorne.Conclusion:This report implies that the baby had an infestation with the larvae of L.serricorne in the gastrointestine.During contact with mud or eating oranges by the girl,worm eggs were swallowed into the stomach and resisted gastric acid digestion which eventually hatched into larvae and caused canthariasis.The 8 months girl had underdeveloped immune system which might facilitate the disease.This report implicates that L.serricorne can infest human accidentally and
