Tom Brooke, PE, MBA, CEM

Transcription

1 Tom Brooke, PE, MBA, CEM

2 Framework, perspective or example in a particular discipline at a given time These four new models are: New and additional, or Updated Today's Paradigm for Air-to-Air Heat Recovery 2

3 1. Standards and Codes 2. The Paradigm s First New Model 3. The Paradigm s Second New Model - The Three Es of Effectiveness, Efficiency, Economics 4. The Paradigm s Third New Model 5. The Paradigm s Fourth New Model - The Three Es of Effectiveness, Efficiency, Economics 6. Summary 7. Questions and Answers Today's Paradigm for Air-to-Air Heat Recovery 3

4 Today s Paradigm for Air-to-Air Heat Recovery 4

5 1. Product Scope (Wheels, Pipes, Plates, Runaround) 2. Uniform Test Protocol 1. Product Scope (Wheels, Plates, Pipes) 2. Performance Ratings at Std Conditions 3. Certification Program *AHRI uses AAHX to refer to these Air-to-Air Heat (and Energy) Exchangers Today's Paradigm for Air-to-Air Heat Recovery 5

6 Dept of Energy 1992 Energy International Policy Act ANSI/ASHRAE Std 90.1 Code Council Today's Paradigm for Air-to-Air Heat Recovery 6

7 Today's Paradigm for Air-to-Air Heat Recovery 7

8 1. Std s climatic zones determine requirements 2. At least 50% enthalpic Effectiveness 3. Ten general exceptions Today's Paradigm for Air-to-Air Heat Recovery 8

9 Today s Paradigm for Air-to-Air Heat Recovery 9

10 -Not Just Effectiveness -A New, Additional Model Today s Paradigm for Air-to-Air Heat Recovery 10

11 1. Effectiveness is the actual heat transfer s % of the maximum heat transfer 2. S, L and T Effectiveness 3. Because of condensation, sensible AAHX can have both sensible and enthalpic Effectiveness 4. Does not consider energy consumed Today's Paradigm for Air-to-Air Heat Recovery 11

12 1. AHRI Guideline V 2. Recovery Efficiency Ratio (RER) 3. Energy Saved/Energy Required to obtain that Savings 4. Similar to Unitary (EER) and Applied equipment (kw/ton) 5. Applies to all AAHX 6. S, L and T Efficiency Today's Paradigm for Air-to-Air Heat Recovery 12

13 1. Includes all peripheral energy losses a. Both airside pressure losses b. Wheel drive motor watts c. Circulating pump watts d. Purge losses (uses lower CFM) 2. RER inexorably links effectiveness and pressure drop 3. Two selections can have same effectiveness but one has superior RER 4. Dimensionless unless combined with associated equipment Today's Paradigm for Air-to-Air Heat Recovery 13

14 Today s Paradigm for Air-to-Air Heat Recovery 14

15 -Not Just Adjacent Counterflow -An Updated Model Today's Paradigm for Air-to-Air Heat Recovery 15

16 1. Traditionally the only layout 2. Lowest cost 3. Highest heat transfer Today's Paradigm for Air-to-Air Heat Recovery 16

17 1. Slight Additional Cost 2. Lower Heat Transfer than Standard Arrangement in Counterflow Application 3. Higher Heat Transfer Than Standard Arrangement in Parallel Flow Application Today's Paradigm for Air-to-Air Heat Recovery 17

18 1. Separation provides airflow design flexibility 2. Up to 100 horizontal if 50 vertical; 40 horizontal if equal heights 3. When vertical difference, higher coil can only be condenser 4. When equal heights, full year operation 5. Valve For economizer control and freeze protection Today's Paradigm for Air-to-Air Heat Recovery 18

19 1. Horizontal separation up to 100 ft 2. Vertical separation up to 30 ft 3. Magnetically coupled fractional HP pumps 4. Pump control for economizer operation and freeze protection Today's Paradigm for Air-to-Air Heat Recovery 19

20 Heat Pipe Configuration Airstreams Airflows Applicability Adjacent Adjacent Separated (up to 100 H, 50 V Separated (up to 40 H) Separated (up to 100 H, 30 V) Counter Flow Parallel Flow Counter/ Parallel Flow Counter/ Parallel Flow Counter/ Parallel Flow Winter/ Summer Winter/ Summer Winter Summer Winter/ Summer Winter/ Summer Today's Paradigm for Air-to-Air Heat Recovery 20

21 WHAT ABOUT EFFECTIVENESS AND EFFICIENCY? Today's Paradigm for Air-to-Air Heat Recovery 21

22 Major Items 1. 10,000 CFM OA; 10,000 CFM EA; 500 FPM 2. Clg plant eff is.75 kw/ton; htg eff is Utility costs per Northwestern Energy 4. LCC factors per NIST/DOE 5. BIN annual energy costs include: a. Full economizer b. Modulated economizer c. Frost control Complete description of all items is in the companion article at Today's Paradigm for Air-to-Air Heat Recovery 22

23 Heat Pipe Configuration MBH Transferred % Sensible Effectiveness Airside PD (Each) Recovery Efficiency Ratio / / / / OA: 20.0ºF DB/18.3ºF WB; EA: 72.0ºF DB/55.8ºF WB Today's Paradigm for Air-to-Air Heat Recovery 23

24 WHAT ABOUT ECONOMICS? Today's Paradigm for Air-to-Air Heat Recovery 24

25 WHERE? 1. ASHRAE 90.1 Climatic Zones 2. Chicago is Roughly Center of Winter Zones Today's Paradigm for Air-to-Air Heat Recovery 25

26 Heat Pipe Configuration Capital Cost $000 Annual Maintenance Cost $000 Annual Energy Saved $000 Twenty Yr LCC $000 (Savings) Today's Paradigm for Air-to-Air Heat Recovery 26

27 1. Fan costs: Since damper space is not always available, this analysis uses valve and pump control for economizer and frost control. If space is available for dampers, some pressure drop may be eliminated for a lower annual fan operating cost. 2. Without a pump in the heat pipe system: a. There will only be winter savings (incorporated), and b. Item one above may also apply (not incorporated). Today's Paradigm for Air-to-Air Heat Recovery 27

28 Today s Paradigm for Air-to-Air Heat Recovery 28

29 HEAT PIPES MAY SELECTIVELY REPLACE ENTHALPIC AAHX! -A Replacement Model Today's Paradigm for Air-to-Air Heat Recovery 29

30 Question: How To Meet ASHRAE 90.1 for 50% Total (enthalpic) Effectiveness Answer: Use an 8 row heat pipe at 350 FPM instead of 6 row at 500 FPM ROWS FPM SENSIBLE EFFECTIVENESS TOTAL EFFECTIVENESS TOTAL RER Today's Paradigm for Air-to-Air Heat Recovery 30

31 Winter DB ºF DP ºF/MCDB ºF /50.6 Summer DB ºF/MCWB ºF DP ºF/MCDB ºF 78.0/ /66.3 Conclusion Latent Recovery Not Needed Today's Paradigm for Air-to-Air Heat Recovery 31

32 * ASHRAE Fundamentals Handbook 1. *No Moving Parts a. Reliable - No emergency breakdowns b. Less maintenance $ 2. *Fan Location Not Critical a. No possibility of cross contamination 3. *Allowable Pressure Differential up to More Compatible with AHU Geometry a. Standard Rectangular coil construction b. Complete cross sectional area is functional 5. No Electrical Connections Today's Paradigm for Air-to-Air Heat Recovery 32

33 1. There are certain geographical regions within North America that have the right weather, and 2. Heat Pipes can easily meet building codes, and 3. The benefits of heat pipes are very valuable to all building owners HEAT PIPES MAY SELECTIVELY REPLACE ENTHALPIC AAHX Today's Paradigm for Air-to-Air Heat Recovery 33

34 1. Mr. Brooke solicits all opinions 2. A broader and more substantive explanation will be published soon at Today's Paradigm for Air-to-Air Heat Recovery 34

35 Today s Paradigm for Air-to-Air Heat Recovery 35

36 HEAT PIPES ARE ECONOMICALLY BETTER THAN A RUNAROUND COIL LOOP <100 -An Updated Model Today's Paradigm for Air-to-Air Heat Recovery 36

37 1. Three way valve maintains: a. Fluid temp ~ 40ºF to EA Coil b. Max SA temp 2. Pump control for economizer Today's Paradigm for Air-to-Air Heat Recovery 37

38 Comparison Logic - All heat pipes selected at common 6R/12 fpi, but runaround fin/tube characteristics different a. Maximize effectiveness 10R/12fpi, 1.8 pump BHP b. Minimize airside PD for min RER 6R/9fpi, 2.4 pump BHP MBH Transferred (1% Design) % Effective ness Airside PD (each) Tubeside PD (each)/ GPM RER Annual Energy Saved $000 Capital Cost $000 Annual Maintenance Cost $ Yr LCC $000 (Savings) a / / b / / Today's Paradigm for Air-to-Air Heat Recovery 38

39 HEAT PIPE HEAT PIPE RUNAROUND HEAT PIPE HEAT PIPE HEAT PIPE HEAT PIPE HEAT PIPE RUNAROUNDD HEAT PIPE RUNAROUNDD % Effectiveness RER Note: Frost and economizer control reduces the heat transfer of the more effective AAHX Today's Paradigm for Air-to-Air Heat Recovery 39

40 CAPITAL COST YR LCC (SAVINGS) $ $ Comparing separated systems, a lower capital cost for glycol will cost the owner dearly! Today's Paradigm for Air-to-Air Heat Recovery 40

41 1. Recovery Efficiency Ratio should be a standard criteria in all AAHX evaluations. Today's Paradigm for Air-to-Air Heat Recovery 41

42 1. Recovery Efficiency Ratio should be a standard criteria in all AAHX evaluations. 2. In addition to the traditional adjacent counter flow airflow design, HVAC system designers now also have access to economically justified adjacent parallel and separated (to 100 ) heat pipe systems. Today's Paradigm for Air-to-Air Heat Recovery 42

43 1. Recovery Efficiency Ratio should be a standard criteria in all AAHX evaluations. 2. In addition to the traditional adjacent counter flow airflow design, HVAC system designers now also have access to economically justified adjacent parallel and separated (to 100 ) heat pipe systems. 3. Recognize that some geographical locations do not need the complexities of latent exchange and heat pipes meet code. Without the latent exchange and moving parts, heat pipes are more reliable, have lower maintenance costs, longer life and zero cross contamination. Today's Paradigm for Air-to-Air Heat Recovery 43

44 1. Recovery Efficiency Ratio should be a standard criteria in all AAHX evaluations. 2. In addition to the traditional adjacent counter flow airflow design, HVAC system designers now also have access to economically justified adjacent parallel and separated (to 100 ) heat pipe systems. 3. Recognize that some geographical locations do not need the complexities of latent exchange and heat pipes meet code. Without the latent exchange and moving parts, heat pipes are more reliable, have lower maintenance costs, longer life and zero cross contamination. 4. With the economics and their compelling advantages, heat pipes are preferred to 100 separation. Runaround coil loops are preferred beyond that, and/or if multiple OA/EA coils. Today's Paradigm for Air-to-Air Heat Recovery 44

45 Tom Brooke, PE, MBA, CEM Today's Paradigm for Air-to-Air Heat Recovery 45