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负压灌溉重液式负压阀设计与试验

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负压灌溉重液式负压阀设计与试验

 34   1 j b [ TA HLNPV 2j4 k W  ›bW A TD aa L PrT[B„yp[ \9 74• Ib 1oM 9 9 j j[25] ”3 71HDF† Ÿ eN‚ €[26-30]9 H 71EE a  Sa8la  Œ11NL ”3 71„D7 OY  3pY   /b V[   V[ A “ -9 9 1 A Œb E1| 9 /Z7 O V9 n b E9 b,E1-“7 O  s,•Yb Ea 6 E 8 ”vbHDE1„NL ”3 71„Di O pb \9/ Œ L P  žv  Pj m 2cbVV 3Z U†sT PT Ÿ A v ” HLNPVrT 1 z7 O[ TArT 1z[ FšTAb[ TA 5Q‚]T ka55  ‚] HLNPV  Pr 4  Kk HLNPV ›  3 CA9  Ah  [ TA H  ›b V 3 HLNPV†sT9  P f ƒ Table 3 Application of HLNPV on some crops under negative pressure irrigation T Crop  Site 9 HWIrrigation duration HLNPV  ”  Pressure and number of HLNPV A Cover liquidHLNPV› ƒ HLNPV running state l’  2014-12-27 2015-02-26 5a7.5a10 kPa 6 F š › z F š Ah  ’ 6 2 2014-06-13 08-10 5a10a15a20 kPa 4 F š › z F š Ah    2014-08-29 10-30 5a10a15a20 kPa 4 F š 5 kPa 25j30 d M‘a 45j50 d‘  j 5 10 kPa 45j50 d M‘ŒB  e 15a20 kPa› zbl’  2015-11-07 2016-01-23 5a10a15 kPa 6 F š › z F š Ah  o 6 2 2015-05-05 07-15 5a10a15 kPa 3 F š › z F š Ah    2015-06-20 09-14 5a10a20a30 kPa 4 F š 5a10 kPa50j55 d M‘ 5 kPaa60-65d‘  j 5 10 kPaB e 20a30 kPa› zb  3 6 2 2015-7-08 09-25 5a10a15 kPa 4 F š › z F š Ah  œˆ 6 2 2016-04-18 06-20 5a10a15a20 kPa 3 F š › z F š Ah   6 2 2016-06-25 09-30 5a10a15a20 kPa 3 F š 5 kPa9 20i25 M‘ŒB  e 10a15a20 kPa› z k’  2016-09-09 11-01 4a8a12 kPa 3 › z  Ah  {  2016-09-09 11-01 4a8a12 kPa 3 › z  Ah   v i 2017-05-20 08-05 5 kPa10 › z  Ah  K  2017-05-20 09-30 5a10a15 kPa 5 › z  Ah  r - ]’  2017-08-01 11-12 10a15a20 kPa 4 › z  Ah  9 HW ›9 HWy1TŒ› s  [1žM€l b Note Irrigation duration refers to the negative pressure irrigation time, inorder to ensure the crop was surving. It begins some days later than sowing or transp lanting. [ F šTA HLNPV  PrT1 {0[ TA HLNPV 9Q‚]T k 3Q k†s HLNPV  3M‘ .‘ j 57 P   bŒ M‘a HLNPV  HW‚M]7 OV[C 3  1  5 kPa„ 10 kPaHLNPVb2014 M› k 5 kPa HLNPV 25-30 M‘a 45j50 d‘  j5 10 kPaHLNPV 45j50 d M‘Œžk  e b 2015 M› k 5a10 kPaHLNPV 50j55 d M‘ 5 kPaHLNPV 60-65‘  j 510 kPa  HLNPV   ž kb7 2016 M6 2›  kž k› 90PŒ 5 kPa  7 SM‘7 O   ž k b  ‚  BŸ ‹/ ‚ b  3Q‹HLNPV  3M‘C V  F š 3 Q‹9 V t k HLNPV› s{; P  s;v 7 3 V ] H   b  bL N[ F šA LVPV – V[ L PV 3 ZU 9 Q‚]T ka 129  F šALVPV  20a 15.5HLNPV 3  CK 8 a 6.2 HLNPV y 7  b a. › z k  H M‘CA  Ah  ba kV 3 M‘CŒ   ž k  ca kV 3  ‘  V  57 . a. The LNPV running very well, no oxide precipitate generated at the whole experiment duration; b. Some black oxide precipitate generated, but can continuously maintained the proper native pressure; c. Lots of black oxide precipitate generated, maybe block up the tube and lose to maintained the proper native pressure. m 2 BW k A TD ƒ Fig.2 Photographs of HLNPV when field experiments were over  1 C9A TD 9 k 89  ‚A TD  ZE1  9A TDHLNPV 1 –‚ ‚ 9  8 “ 4ž D –V  b ƒ f ƒ9b T TA –‚ 3CŒ ‚  BŸ TT 3 1  V1QFTA 9F byN1sBŸl‚ b a  3Q‹Ab 3 “ - HLNPV‚  “db HLNPV e5 —Ÿ  e  T1T‚] 3‚]AHLNPVt‚ZLb T| e5  Ÿa  VA –vv4ZLŸ  “db  ‚ 4NM  U ˜j 5a S ˜j 5a bj o[ ƒ €W›  9“d 9 A TDHLNPV     F š  A ] b  k i HLNPV e› _BW HLNPV erT› 41s HLNPV 9“dC Ÿ S | [/ ‚ 1HLNPV   sO q„ ’ sO q 0.1 kPa 30 kPa[ /Ml 5b 2v†s HLNPV  LBWHq/  ›b[ TA 5T  55 HLNPV 2j4 k W ›b[ F šTA 9 T  129  LVPV 2j3  k W  15.5 3  M‘C  6.2y‘  57•Y  b 3HLNPV MCZE A1  ]b 5.0j20.0 kPa/  Ea,Ea Ea  6 E 9.6j17.28a l  Ea  6 aHD‚,aHD * “1 9‚  *“  HW/›b 98  HLNPV 1  ’ HW“d S“d a8la  a  keL V[9}CZEb † †  ju l C . B aRr › ]S [J].  j C . r › ] K 3 { Ÿ•Y [J]. S S 2015361 3541. Xiao Haiqiang, Liu Xueyong, Long Huaiyu, et al. The effects of soil water potential on the growth and water consumption of flue-cured tobacco[J]. Chinese Tobacco Science, 2015, 361 3541. in Chinese with English abstract [28] oZ  . 9 K 3 g  q•Y [J]. S . 2016222 5260. Xiao Haiqiang, Ding Yahui, Huang Chuyu, et al. Effect of negative pressure irrigation on water fertilizer utilization and flue-cured tobacco growth[J]. Acta Tabacaria Sinica, 2016, 222 5260. in Chinese with English abstract [29] u    C c . 9/‚]K l’ 3•Y [J]. S j S 2017504689697. Zhao Xiujuan, Song Yanyan, Yue Xianlu, et al. Effect of different potassium levels on the growth of bok choy under negative pressure[J]. Scientia Agricultura Sinica, 2017, 504 689697. in Chinese with English abstract [30] 3   C .  gB89 „ a‹ r q•Y [J]. g  201723 2 416426. Li Shengping, Wu Xueping, Long Huaiyu, et al. Water and nitrogen use efficiencies of cucumber under negatively pressurized fertigation[J]. Journal of Plant Nutrition and Fertilizer, 2017, 23 2 416426. in Chinese with English abstract Design and experiment of heavy liquid-type negative pressure valve used for negative pressure irrigation Long Huaiyu, Zhang Huaizhi, Yue Xianlu, Zhang Renlian Institute of Agriculture Resources and Regional Planning, Chinese Academy of Agriculture Science, Beijing 100081, China Abstract Negative pressure irrigation NPI is a high efficient irrigation technology which has attracted great concern from some Chinese scholars in the past decade. To produce and maintain a steady negative pressure is an essential key point for NPI, and at present there are mainly 5 s, namely hanging water column HWC, static water column SWC, climbing water column CWC, electromagnetic valve EMV and negative pressure water circulation NPWC. However, due to some inherent shortcomings, those s are not convenient to practically operate. The HWC is easily to fail due to the air embolus, the EMV and NPWC are energy-consuming, and too large heights of HWC, SWC, CWC and NPWC make them very cumbersome and not easy to install. In fact, the negative pressure results in the soil water sopping, which is always continuous, slow and unidirectional, and the function of the negative pressure maintaining device is similar to negative pressure limiting valve which does not need to act continuously or high frequently. Therefore, the heavy liquid static pressure should be theoretically used to control the negative pressure in the NPI system. It is known that 1 mmHg which can be easily determined with naked eyes can generate 0.133 kPa static pressure. Moreover, the negative pressure in actual NPI is seldom set under -30 kPa which is equivalent to 22.5 mmHg. Obviously, the negative pressure maintaining device using the static pressure of mercy whose density is the largest in the world to control the negative pressure in NPI should have high precision and small size, and be easily to operate. Accordingly, a heavy liquid-type negative pressure valve HLNPV was designed. The HLNPV consists of 3 basic interconnected parts, i.e., a U-shaped tube, an S-shaped pressure maintaining tube and a hollow ball, together with a certain amount of mercury which can be poured into them and cyclically flow in them. The negative pressure is maintained by the static pressure of the mercury in the S-shaped tube. Additionally, a device to slow down the air entering was installed between HLNPV and atmosphere, and the mercury in the hollow ball was overlapped by paraffin oil or water to prevent the evaporation of mercury. Laboratory test showed that the precision of HLNPV could reach 0.1 kPa, which is too enough for NPI, and the relative error of HLNPV with the theoretical control pressure from -5 to -30 kPa was less than 5, which is satisfactory for NPI. In the field, most paraffin oil overlapping HLNPV could steadily run for the whole experiment period of 2-3 months, while the mercury in 15.5 of the HLNPV was oxidized after running for 1-3 months, and that in 6.2 of the HLNPV was blocked up by the oxide precipitate, which caused their failure to maintain negative pressure. Water-overlapping HLNPV could steadily run for the whole experiment period of 2-4 months, while water is a theoretic volatile liquid, if the runtime is more than 4 months, the overlapping water maybe need to be complemented. In one word, the HLNPV can overcome many disadvantages of the present negative pressure maintaining s, and has the advantages of larger negative pressure, no energy consumption, small size, high accuracy, easy to install and debug, as well as more security. The mechanism, structure, application effect and suggestions for improvement of the HLNPV are described explicitly in this paper, thereby providing a reference for its further application, innovation and improvement. Keywords irrigation; design; agriculture; heavy liquidtype negative valve; negative pressure irrigation; negative pressure maintaining

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