1. Waste Heat Recovery & Heat Pumps
Dave Pearson
Star Renewable Energy
An introduction discussing - Why do Maintenance?
Highlight factors such as:
Reliability – Confidence in the plant and low human interference
Efficiency – Getting the best from your asset at all times
Health & Safety – Being a low risk and ensuring no failures that could lead to accidents
Legal Compliance – Fulfilling the necessary compliance eg F-Gas, Written Scheme of Examination, PSSR etc
Uptime/Productivity – Ensuring the plant is available at all times to deliver the necessary cooling demands
Environment – Keeping the plant in the best condition to avoid losses that may impact the environment eg refrigerant leaks
Corporate and Social responsibility – A demonstration that your business does what is right!
All of these are inextricably linked by money, but the investment in maintenance can capitalise in your return in all of them.

2. SRE & Heat Pumps

3. SRE & Heat Pumps
ASHP
Up to 62C hot water flow
WSHP
Between
20C and 90C
Hot water flow

4. Big Heatpumps @ Drammen

5. The Basics – WSHP

6. The Basics ASHP

7. Refrigeration Cycles
Relationships between the different stages in the cycle

8. Refrigeration Cycles
Increase the source Temp, Decrease the Hot side Temp

9. Refrigeration Cycles
Add in a Subcooler

10. Refrigeration Cycles
Add In A Desuperheater

11. Heat recovery summary
Not much for free- the more you try the more you get
Beware of “fake-news”
More “considered” plant likely to be better in general and offer more heat recovery

12. Operating Temperature – Source Side

13. Operating Temperatures – Hot Side
This is the district heating side of the heat pump system
Doesn't have to be 82/71 Deg C – This is for GAS!
Doesn’t have to be 90 Deg C just because we did it at Drammen

14. System Design - Basic
2MW 55/75
from 8/5 Deg C Source
Water entering condenser and oil cooler independent
of each other and mixing to achieve the desired
outlet temperature
COP of around 2.2

15. Including a Desuperheater
COP increased to 3.0

16. Including Subcooler (but no Desuperheater)
Including a Subcooler but no Desuperheater takes the COP
to 2.99

17. Both Subcooler and Desuperheater
COP now at 3.08

18. What About Subcoolers & Desuperheaters?

19. Multiple Heat Pumps – Parallel or Series or Both?
3 heat pump system
Parallel Vs Series/Parallel Combination for 2MW 55/75
from 8/5 Deg C Source
Parallel gives COP: 3.08
Combination gives COP: 3.39

20. Single, Double, Triple

21. More Complex

22. 18MW District Heating

23. “Free Cooling”
Evaporator outlet water.
Smart city planning.
Reduce cost for electric cooling on site.

24. Hot side flow/return Temp (Deg C) 55/75 Source Side Temp (Deg C) 8/5
Motor Losses and Source Pump Power!
Are you being quoted a Shaft or Absorbed power COP??
Hot side flow/return Temp (Deg C)
55/75
Source Side Temp (Deg C)
8/5
Number of Units 1
Heat Pump Capacity (kW)
1049.5
Power - Shaft (kW)
332.4
COP
3.16
Motor Losses - Say 3% (kW)
9.972
Inverter Losses Say 3% (kW)
New COP
2.98
Source Pump Power (kW) 20
Final COP
2.82

25. Why Should We Care?????????
Larger central energy plants = lower cost (£/kW)
RHI
Waste heat provides opportunity for very high COP’s
Carbon reductions (Carbon targets)
The electricity gird is decarbonising every year. Why wouldn’t you want technology
that is 2050 ready?

26. Gas Elec HP1 HP2 Fuel(kWh) 3 10 Efficiency(%) 85% 100% 600% 300%
How much is that doggy in the window?
So 1kWh from 4 sources……………
HP1 = Heatpump COPh 6.0
HP2 = Heatpump Coph 3.0 but RHI eligible…………………………...
Gas
Elec
HP1
HP2
Fuel(kWh) 3 10
Efficiency(%)
85%
100%
600%
300%
RHI(p/kWh)
5.5
nett Fuel(kWh)
3.53
10.00
1.67
3.33
nett Heat (kWh)
-2.17
nett Fuel (KgCO2 /kWh)
0.225
0.35
0.058
0.117

27. Looking To The Future

28. Main rates of CCL Carbon Reduction Commitment and Climate Change Levy
CRC end Oct 2019
CCL takes up the reins.
Main rates of CCL
Taxable commodity
Rate from 1 April 2016
Rate from 1 April 2017
Rate from 1 April 2018
Rate from 1 April 2019
Electricity
(£ per KWh)
102%
103%
145%
Natural gas
(£ per KWh)
167%

29. The choice?
Listen to “Policy Needs” and act for the future now
Or wait till the Carrot is a just a faded memory!