Zuba-Dan Inverter New Mr.SLIM Inverter for colder climate regions

Transcription

1 Zuba-Dan Inverter New Mr.SLIM Inverter for colder climate regions Mitsubishi Electric Corporation Shizuoka Works 2007 JSRAE Technology Award

2 Mr. SLIM Zuba-Dan Inverter models 1. Development background 2. Features of Zuba-Dan models 3 Flash Injection Cycle & its characteristics 4. Improvement on Start-up & Defrost 5. Field Test Result 6. Summary

3 1. Development Background

4 1. Development Background <Min. Temp. in January> (average of 1991 to 2000) -15 to -20 o C in Northern part of Hokkaido. Around -10 o C in Southern part of Hokkaido and in Tohoku region

5 1. Development Background <in case of Standard Heat Pump air conditioner> Capacity is reduced at low ambient temperature. Electric heater assisted indoor unit Burner assisted indoor unit 0.8 Liquid injection Heat Pump 0.6 Capacity is reduced by defrost operation which leads to poor comfortability Heating Peformance Curve

6 1. Development Background Challenges for Heat Pump *Poor performance at low ambient temperature. *Room temperature goes down during defrost. Slow in starting up. *Not adequate for use in northern part of Hokkaido. Electric Heater assisted A/C > Low in operation efficiency. Burner assisted A/C > Periodical servicing is required for burner. > Requires big installation space. > Big amount of the initial investment. Liquid INJ COMP mounted A/C > Limited in injection amount (discharge temperature goes down too much) > Operation efficiency should be improved during injection. Required functions for A/C for cold climate regions (1)No periodical servicing is required. (2)Keeps good performance even at low ambient temperature. (3)Highly efficient operation at low ambient temperature. (4)No drop in room temperature while defrosting. (5)Can be used in all areas in Hokkaido. solution: Zuba-Dan

7 2. Features of Zuba-Dan models

8 2. Features of Zuba-Dan models (1)High heating capacity at low ambient temperature Our Flash Injection cycle (patent to be filed) enables to keep the maximum heating capacity even at -15 o C. (2)Comfortability *Improved defrost control: Defrost duration is reduced to one third of the conventional model. *Quick start-up: Required time to reach the air blowing temperature of 40 o C is halved. (3)Wider operation range <Industry First!> Heating operation even at -25 o C is possible. (conventionally only to -20 o C) > Possible to be used in all areas in Hokkaido. (4)Easy and quick installation <Industry First!> The Activated carbon filter and the Wide strainer enable the reuse of existing piping even when the compressor is broken and the refrigerant oil is contaminated.

9 3. Flash Injection Cycle & its characteristics

10 3. Zuba-Dan refrigerant circuit <Flash Injection + Power Receiver Circuit> Outdoor unit 4-way valve Indoor unit Outdoor HEX C Injection Compressor Indoor HEX B K A Power Receiver (Heat recovery type liquid pool) H G HIC F D J E LEV A <Characteristics> LEV C LEV B : Refrigerant flow in heating mode *Flash Injection of refrigerant. Refrigerant heat is recovered by HIC circuit. *Power Receiver circuit without inlet accumulator (good in start up / inlet dry control) *3 LEVs optimally control evaporator, condenser and discharge temperature.

11 3. Zuba-Dan refrigerant circuit <Zuba-Dan refrigeration cycle (Pressure-Enthalpy diagram)> 10 Heat Exchange by heat recovery type receiver Pressure[MPa] 1 Increased refrigeration effect G Heat Exchange by HIC F J D E K Injected Gas gets drier >>> Injection amount is increased. (To prevent discharge SH to decrease.) B C H I A 0.1 (1)Increased refrigeration effect (improved refrigerant cycle theory) (2)Quick recovery from defrosting with no accumulator. (3)Inlet gas super heat >>> to secure compressor high efficiency (to avoid liquid compression efficiency to be lowered) Enthalpy[kJ/kg]

12 3. Zuba-Dan refrigerant circuit <Flash Injection Cycle> Outdoor unit 4-way valve Indoor unit 10 Heat Exchange by heat recovery type receiver Outdoor HEX H G K HIC J C B F A Injection Compressor Power Receiver (heat recovery type liquid pool) E D Indoor HEX Pressure[MPa] Increased refrigeration effect G Heat exchange by HIC H F J D E Enthalpy[kJ/kg] K B I A C LEV A LEV C LEV B : refrigerant flow in heating mode (1)Increased refrigeration effect (improved refrigerant cycle theory) (2)Quick recovery from defrosting with no accumulator. (3)Inlet gas super heat >>> to secure compressor high efficiency (to avoid liquid compression efficiency to be lowered)

13 3. Zuba-Dan refrigerant circuit <Comparison with conventional injection> Discharge temperature increases >>> capacity cannot be increased a lot = not suitable for a/c for cold regions. Injection Compressor Evaporator Condenser Gas/Liquid separator HIC X=0.2 X=1.0 X= Liquid INJ Gas INJ Flash INJ

14 3. Zuba-Dan refrigerant circuit <Comparison of Flash INJ with Liquid INJ (same capacity basis)> 10 Inside HEX without HIC Conditions: Ambient-15 o C / COMP 120rps / Heating capacity 14kW Liquid INJ (w/o HIC) Pressure[MPa] 1 Gi Ge Qc Pd COMP input = 7.13kW Pinj Big amount of liquid injection >>> discharge temperature decreases. Ps Qe Enthalpy[kJ/kg] Flash INJ Pressure[M Pa] 10 1 Inside ŕ MŚđŠ ŠíHIC L HEX with č Conditions: ŹđŚŹFŠO C-15 Ambient-15 Ž A łź o C / ń ] 120rps COMP 120rps A g [ \ Í14kW / Heating capacity 14kW Qc COMP input ü Í=6.14kW = 6.14kW Inlet gas gets drier >>> discharge SH can be secured. Qe Enthalpy[kJ/kg]

15 3. Zuba-Dan refrigerant circuit <Flash Injection circuit> 10 Inside ŕ MŚđŠ ŠíHIC HEX without ł µ HIC Conditions: ŹđŚŹFŠO C-15 Ambient-15 Ž A łź o C / ń ] 120rps COMP 120rps A g [ \ Í14kW / Heating capacity 14kW Liquid INJ (w/o HIC) Flash INJ Pressure[M Pa] Enthalpy[kJ/kg] Pressure[M Pa] 10 1 Gi Ge Qe Qc Pd ü Í=7.13kW COMP input = 7.13kW Inside ŕ MŚđŠ ŠíHIC L HEX with č Conditions: ŹđŚŹFŠO C-15 Ambient-15 Ž A łź o C ń ] 120rps / COMP 120rps A g [ \ Í14kW / Heating capacity 14kW Qc Pinj Ps ü Í=6.14kW HIC with HIC L č HIC w/o HIC ł µ Ge kg/h Gi kg/h fźő Ęß Ë Ä deg 20 0 ń ] rps Qc W Qe kw ü Í input kw cop 2.28(116%)1.96(100%) discharge SH COMP rotation Qe Enthalpy[kJ/kg]

16 3. Zuba-Dan refrigerant circuit <Theoretical characteristics: calculation conditions> Sub cool 10deg 3.063MPa(50 ) Condenser refrigerant amount Ge+Gi 0.908MPa T5:HIC inlet liquid temperature T7:HIC outlet liquid temperature Tm: Injection refrigerant temp. Equal entropy compression 0.269MPa(-30 ) Injection amount Gi Evaporator refrigerant amount Ge Super heat 10deg *Pomer množstiev α=gi/ge *HIC temperature efficiency ε ε=(t5-t7)/(t5-tm)

17 3. Zuba-Dan refrigerant circuit <Theoretical characteristics: temperature efficiency influence> 1.35 Ratio of Heating COP & Capacity (base condition α=ε=0 ) ratio of Capacity ratio of COP HIC Temperature Efficiency ε As HIC temperature efficiency increases, heating capacity and COP also increase.

18 3. Zuba-Dan refrigerant circuit <Test Result (1)> Discharge Pressure[MPa] HIC Length 0m 1.5m 3m Discharge Temperature[ ] HIC Length 0m 1.5m 3m Injection Ratio α Injection Ratio α *Discharge pressure increases as Injection ratio increases. It has got no relations with HIC length. *Discharge temperature decreases as Injection ratio increases.

19 3. Zuba-Dan refrigerant circuit <Test Result (2)> Heating Capacity Ratio[ ] HIC Length 0m 1.5m 3m Heating COP Ratio[ ] HIC Length 0m 1.5m 3m Injection Ratio α Injection Flow Ratio α *Heating capacity gets bigger as the HIC length gets longer. It depends on the Injection ratio as well but not largely. *COP worsens as the Injection ratio gets bigger. 125% Heating capacity / 100% COP is realized when injection ratio is 0.4.

20 3. Zuba-Dan refrigerant circuit <Heating capacity at low ambient temp. (comparison with conventional model)> Heating Capacity[W] FLASH Injection Rotational Speed 100% Outdoor Temp. m Ž n FLASH Injection Rotational Speed 70% Conventional Rotational Speed 70% *Heating capacity is improved by 30% even at same COMP rotation speed (at -15 o C) *Heating capacity is almost doubled with increased COMP rotation speed. (at -15 o C) >>>This was impossible before due to the excessive temp.rise of discharge refrigerant.

21 3. Zuba-Dan refrigerant circuit <Flash Injection Cycle Control> SC DischargeSH džq c Ł Ů LEV B B džq c Ł Ů LEV C C 3 conditions (suction refrigerant, condenser and evaporator) is optimally controlled. <LEV> <controls on> A: Suction refrigerant Super Heat B: Condenser Sub Cool C: Discharge refrigerant Super Heat džq c Ł Ů LEV A A SuctionSH

22 3. Zuba-Dan refrigerant circuit <LEV characteristics> Refrigerant distribution is analyzed when each LEV is controlled individually fźosh discharge SH SC SC 30 z üsh suction SH fźosh discharge SH SC 30 z üsh suction SH 25 fźosh discharge SH SC z üsh suction SH SH,SC[deg SH,SC[deg SH,SC[deg Lower LEV ş ilevš opening J x[pulse] (pulse) Upper Źă ilevš opening J x[pulse] (pulse) INJ INJLEVŠ opening J x[pulse] (pulse) Only suction SH responds to line SH shape. SH Suction Super Heat control Influence on refrigerant distribution. SC Sub Cool control Discharge SH responds acutely. SH SH Discharge Super Heat control

23 3. Zuba-Dan refrigerant circuit <Application of Quality Engineering> <Background> *3 LEVs operates individually towards different control targets. *Does individual LEV control interfere each other resulting in unstable refrigerant cycle? *Most stable control constant is chosen. <Purpose> We apply Quality Engineering in order to check whether the currently chosen control constant combinations (current control) is appropriate or not.

24 3. Zuba-Dan refrigerant circuit <System Basic Functions> *What is the stability of the refrigerant cycle? <Definition of Basic Function> Starting from the stable condition, compressor rotation should be increased from 60 to 70rps. If the integrated value of SHs in the next 10 minutes is small, it means the stability is high. SHs 11deg 10deg 9deg SHs time σ 2 = 600 t= 1 ( SHs) 600 2, SHs = SHs 9 L( SHs < 9) SHs = SHs 11L( SHs > 11) SHs = 0 L(9 SHs 11)

25 3. Zuba-Dan refrigerant circuit <Injection Pressure calculation method> Vst1[cc/r] = Compressor s suction volume Pd Vst2[cc/r] = Compression room volume at the end of injection Pm *Point 1 Inlet refrigerant (density D1) is trapped in Vst1. *Point 1 >>> 2 8 Injection refrigerant (condition 9) is poured h2 into compression room 7 Existing refrigerant amount increases to D1 (1+α). α *Point 2 >>> 3 Injection port is closed at the compression room volume of Vst2. Normal pressure rise process afterward. h Gi 9 2 Ge = Gi / Ge 1 3 Ps Pinj By adjusting the discharge SH at point 3 by α, and by adjusting Pinj to make the density at point 2 gets D2, Injection pressure can be calculated.

26 3. Zuba-Dan refrigerant circuit <Injection Pressure> Pd: stable, Ps: variation character Pressure (MPa (abs)) [MPa(abs)] Pd Pinj(SHd20deg) Pinj(SHd50deg) INJ α INJ ratio α INJ ratio (SHd20) (SHd20) INJ ratio (SHd50) Ps[MPa(abs)] Ps[MPa(abs)] Pinj is about 2.5 times of Ps. INJ amount (discharge SH) has just small influence. The lower the Ps is, the bigger the INJ ratio α gets. The smaller the discharge SH is, the bigger the α gets.

27 4. Improvement on Start up & Defrost

28 4. Improvement on Start up & Defrost <Standard Accumulator circuit> Refrigerant is pooled in the accumulator during start up and defrosting. As a result, it takes long time to start up due to insufficient refrigerant circulation. Normal start up: Refrigerant within outdoor HEX moves into the accumulator. Defrost: surplus refrigerant is pooled in the accumulator. <Flash Injection cycle> (1)Start up with a bit return in liquid condition as there is no liquid pool on low pressure side. (to secure circulation amount) (2)Refrigerant pooled in the receiver during defrost is quickly let return to compressor from injection circuit. It contributes to improve start up characteristics. (3)Refrigerant circulation amount at start up is secured by Injection. Outdoor unit 4-way valve Outdoor unit 4-way valve Compressor Injection compressor Slowly return to suction through oil recovery hole. Accumulator Power receiver HIC

29 4. Improvement on Start up & Defrost <Start up characteristics (at -10 o C ambient)> Zuba-Dan air discharge air temp ( ) Air discharge temp ( o C) Accumulator cycle air discharge temp Zuba-Dan low pressure Low pressure (MPa) ( Accumulator cycle low pressure Time (minute) (min) In accumulator cycle, the temperature does not rise rapidly due to insufficient refrigerant circulation when starting up. On the other hand in Zuba-Dan, the discharge air temperature can reach high level in short time.

30 4. Improvement on Start up & Defrost <Better comfort with better defrost control> Better comfort is achieved by Flash Injection cycle and new Defrost control. (1)Quicker start up *Optimal supply of refrigerant by receiver circuit at start up. *Refrigerant circulation amount is increased by Flash Injection. (2)Shorter defrost *Defrost is shortened by Flash Injection. (3)Less frequent defrost *Less frost on HEX with hydrophilic fins. *Estimation control on Frost formation contributes to reduce defrost frequency largely, especially in low ambient temperature (low absolute humidity).

31 5. Field Test Result

32 5. FT Result (1): Office building in Asahikawa City <Tested units and conditions> *Test Period: From December 2004 to February 2005 *Test Location: At an office building in Asahikawa, Hokkaido *Test Points Žş Outdoor unit: 11.2kW 11.2Kw class unit N X Žş Indoor unit: 2 units 5.6Kw of 5.6kW N class X ~ c C zšç Piping length: about ń 15m 15 Ť Śä Žd Š â n Śä( ÝĽŢŞ Ľ Ý L) A ĘŹí (2)w/o Śä( ÝĽŢŞ Ľ Injection (normal control) Ý ł ) A đśđśý ÉŽŔŽ{ Ş Test čť Ú points: *Indoor Žş inlet ŕ z & outlet Ťž/ temperature o x Ź Žş ŕ x Ş zašo C xa â } xa ŹÁ ď d Í Ę Control specifications: (1)with Injection (control for cold regions) *(1) & (2) are both realized alternatively. *Indoor temperature distribution, Ambient temperature, Refrigerant temperature, Energy consumption

33 5. FT Result (1): Office building in Asahikawa City Outdoor unit 2 Indoor units

34 5. FT Result (1): Office building in Asahikawa City Heating Capacity & COP based on the different ambient temperature Heating capacity: (indoor outlet inlet) x air volume x density x specific heat Heating capacity (kw) g [ \ Í(kW) Basic cycle Heating Capacity Basic cycle Šî {» Ů catalogue specifications g [ \ Í(kW) Heating capacity (kw) Injection cycle Heating Capacity Zuba-Dan ŢĘŢ g ŘŃ Ambient ŠO temperature C x ( ( Ž) o C) Ambient ŠO temperature C ẋ ( Ž) ( o C) without INJ >>> with INJ Capacity increases by about 30%

35 5. FT Result (1): Office building in Asahikawa City <Quicker Start up in Heating operation> Indoor Unit mž n Ž Injection Cycle Normal Cycle Time mmin. n <with Injection> *Indoor outlet temperature in stable condition >>> more than 50 o C *To reach indoor outlet temperature of 45 o C >>> takes only about 10 minutes (when unit starts running at the ambient temp of -15 o C and at the indoor room temp of 23 o C) <Shorter start up> about ½ of conventional model

36 5. FT Result (1): Office building in Asahikawa City <Defrosting characteristics> <data taken between 25 Jan 2004 (noon) and 26 Jan 2005 (noon)> indoor Žş ŕ o Ź x Žş indoor ŕ x room ŠO C ambient x outlet temp. temp. temp. Temp. mž n (1) (2) :00 14:00 16:00 18:00 20:00 22:00 0:00 2:00 4:00 6:00 8:00 10:00 Time mhour n <ambient temp.: -20 o C> (1)continuous operation of more than 150 min. (2)Defrosting only for about 3 minutes.

37 5. FT Result (1): Office building in Asahikawa City <Defrosting characteristics (operation ratio)> 100% Basic cycle Šî {TCN Flash Injection cycle Ě ŻĽ- ÝĽŢŞ Ľ Ý» Ů 98% operation ratio ^ ] 96% 94% 92% 90% ŠO C ẋ( ) minimum temperature in a day <Heating operation ratio> (Heating operation duration Defrost duration) / (Heating operation duration) As the ambient temp. decreases (below 0 o C), the average heating operation ratio increases. >>> The operation ratio improves more by extending the continuous operation duration with no frost on the coil.

38 5. FT Result (2): Station waiting room (in Niigata pref.) Feb 2006 (wooden building, door is opened frequently) 4HP wall mounted type indoor unit for about 30m 2 room.

39 5. FT Result (2): Station waiting room (in Niigata pref.) <Measured Data> From am to on 12 Feb Humidity: % Exceeds 45 o C in 18 min. from start up. (Room temp. at start up was about 8 o C) Outlet Temp. 35 Temp. ( o C) ( ) Room Temp. lowered by 2 o C during defrost Indoor Temp Defrost (5 times in 12 hours) 0-5 Ambient Temp :00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 0:00 Hours (o clock) Much better comfort can be achieved by quicker start up of heating operation and improved defrost control.

40 6. Summary

41 6. Summary: Following functions are realized as the A/C for cold regions (1)Improved Heating Performance *High heating performance & high COP achieved by Flash Injection. *Operation range extended down to -25 o C. (2)Better Comfort *Start up and Recovery from defrost are improved very much by Injection together with Receiver circuit. *Defrosting frequency at below 0 o C ambient is reduced to about 1/3. (3)Exsisting piping can be reused even though the compressor was broken down. *Since its launch in July 2005, Zuba-Dan has been highly appreciated in cold regions such as in Hokkaido. *Zuba-Dan technology has also been adopted to our City Multi (VRF) since December 2006.

42 ZubaDan What do you expect from ZubaDan? For which application do you need ZubaDAN? How do you calculate the cooling and heating capacity Can you use Zuba Dan Air to Air without cooling function? Which price is accaptable in comparison to Power Inverter? 5% 10% 20% 30% 40% 50 %

43 Thank you very much!