GEOTHERMAL GROUNDSOURCE HEAT PUMPS

1

• Research on Heat Pumps in México Operating on
  Geothermal
• and Waste Energy as Heat Source
• A. García-Gutiérrez, R. Barragán-Reyes y V.
  Arellano-Gómez
• Instituto de Investigaciones Eléctricas
• Cuernavaca, Morelos, México
• Geothermal Resources Council Annual Meeting
• Reno, Nevada, USA
• September 30 October 3, 2007
• AGENDA
• Introduction
• Present situation - International
• Previous work in México
• Mechanical Compression Heat Pump
• Absorption Heat Pump
• Type-II Absorption Heat Pump - Heat Transformer
• Conclusions

2

• Research on Heat Pumps in México Operating on
  Geothermal
• and Waste Energy as Heat Source
• Introduction
• HP- a thermal machine that operates like a
  refrigerator but in reverse
• Refrigerator main purpose cooling
• HP main purpose heating, heat amplifiers
• Both produce the two effects simultaneously
• HP extracts heat from, typically from a grade a
  low-source at TS, like geothermal low-pressure
  steam, separated water or underground heat, or an
  industrial effluent, and delivers energy at a
  more useful temperature level, TD
• This is accomplished by using a small amount of
  high-grade energy, like mechanical energy -
  electricity, or high-temperature thermal energy,
  depending on the HP type
• Coefficient of Performance - a measure of their
  effectiveness to provide useful heat in relation
  to the direct use of a high-grade energy source

3

• Research on Heat Pumps in México Operating on
  Geothermal
• and Waste Energy as Heat Source
• HP types
• (1) Mechanical compression,
• (2) Absorption, and
• (3) Heat transformers, the so-called Type 2
  Absorption Heat Pump

Schematic diagram of a MCHP

• Heat flows from lower to higher temperature
• Uses electricity to do work pumps heat
  uphill
• Source - Heat absorbed in the Evaporator
• Sink at TD - Heat delivered in the Condenser
• Gross temperature lift (TCO TEV)
• As (TCO TEV) increases, more power is required
• Simultaneous cooling and heating reversible
  operation

4
Taken from J. Lund, Geothermal (Ground-source)
Heat Pumps, Presented at IIE, Cuernavaca,
México, 2007
5

• Investigación sobre Bombas de Calor en México
  Operando con Energía Geotérmica y Calor de
  Desecho
• Present situation - internacional (Rybach, 2006
  Lund , 2007)
• Geothermal Heat Pumps GCHPs represent the
  geothermal technology sector with the fastest
  growth
• In 2005, 33 countries used GCHPs for heating,
  cooling and hot water domestic water
• The installed capacity of GCHPs increased some
  730 in the last 10 years and the us of energy
  for heating grew 500.
• Capacityd 15,400 MWt 24,300 GWh/yr
• Main developments in some European countries and
  USA Los principales desarrollos se realizaron en
  algunos países de Europa y en EUA
• Growth - 3 to 4x since 2000
• Typical unit - 12 kW (3.4 tons) - Range 5.5 kW
  to 150 kW
• Installed units - 1.3 millions (LF 0.17)

6
Present situation international (Rybach, 2006
Lund , 2007) USA designed for cooling /AC,
over-designed for heating 1,200 full load
heating hrs/year, CF 0.14 Europe designed
for base heating 2,000 a 6,000 full load
hrs/year, typical 2,200 hrs, CF 0.23 0.68

• Largest HP installation - Galt House East Hotel,
  Louisville, KY
• Heating and A/C for
• 600 hotel rooms 100 apartments
• 89,000 m² of office space Total 161,650 m²
• Uses 177 l/s from 4 wells _at_ 14C Provides 5.8
  MW cooling and 19.6 MW heating
• Energy use approx. 53 of similar non-GHP
  building
• Savings 25,000 US dlls per month

• Country MWt GWh/yr Number
• Austria 300 400 25,000
• Canada 446 600 37,000
• Germany 400 610 33,000
• Sweden 3,840 10,000
  320,000
• Switzerland 532 800 44,000
• USA 8,400 7,200
  700,000

7

• Research on Heat Pumps in México Operating on
  Geothermal
• and Waste Energy as Heat Source
• Previous work in México
• Frías et al. (1991) installed and tested a
  mechanical compression HP at the Los Azufres
  geothermal field for brine purification purposes
  using low-pressure geothermal steam
• Best et al. (1986 1990) installed and tested an
  ammonia/water (NH3/H20) absorption heat pump for
  cooling/refrigeration in Los Azufres and Cerro
  Prieto geothermal fields
• Barragán et al. (1998) tested in a laboratory
  several ternary solutions in an absorption heat
  transformer
• Ayala (1995) studied experimentally a H20/LiBr
  which is used commercially for refrigeration
• Rivera et al. (1999) evaluated experimentally a
  mixture of H20/CarrolTM as a working fluid in a
  single stage heat transformer
• Santoyo et al. (2006) describe an experimental
  work on a HP-assisted distillation system
  operating on industrial effluents aimed at the
  obtention of purified water from geothermal
  brines or similar
• IIE plans to install and test a GCHP in the
  Cerro Prieto/Mexicali area

8

• Research on Heat Pumps in México Operating on
  Geothermal
• and Waste Energy as Heat Source
• Mechanical compression HP installed and tested at
  Los Azufres geothermal field (Frías et al., 1991)
  
• Westinghouse Electric, model TPB20, with two
  working fluid circuits
• Capacity 56 kWt _at_ 71C, COPA 4.74 with heat
  source at 52C
• Working fluid Freón R114

Coefficient of Performance HP Effectiveness
9
Research on Heat Pumps in México Operating on
Geothermal and Waste Energy as Heat
Source Mechanical compression HP installed and
tested at Los Azufres geothermal field (Frías et
al., 1991)
COPC COPR COPA
MAIN RESULTS Brine distillation rates 28 kg/hr
COPA 3.8 _at_ 83C (HPER) 0.4 - 0.6
10

• Research on Heat Pumps in México Operating on
  Geothermal
• and Waste Energy as Heat Source
• Absorption HP (Best et al., 1986 1990)
• Cooling capacity 10.5 kWt
• NH3/H20 - 35.7 kg/49.3 kg 0.75 kg Sodium
  Chromate as corrosion inhibitor)
• Built with carbon steel materials, except
  generator helical coil
• Condenser and evaporator capacities 17.6 y 10.6
  kWt
• Generator, rectifier and pre-mixer Shell and
  tube HXs
• Operated with geothermal heat at Los Azufres and
  Cerro Prieto.

Actual, Carnot and Rankine Coefficients of
Performance Flow Ratio
11
Research on Heat Pumps in México Operating on
Geothermal and Waste Energy as Heat
Source Absorption HP (Best et al., 1986 1990)
MAIN RESULTS COPA 0.35-0.45 Cooling capacity
10.3 kW Generator temperature 91.5C
Evaporator temperaure -13C Useful for
refrigeration and storage of perishable food, as
in the Cerro Prieto agricultural area
12

• Research on Heat Pumps in México Operating on
  Geothermal
• and Waste Energy as Heat Source
• Heat Transformer Type - II Absorption Heat
  Pump (HT-HP)
• A quantity of heat is provided at a temperature
  TM
• A fraction of which is rejected at a lower
  temperature TO
• The remaining energy is upgraded to a higher
  temperature TH
• HT-HPs recover 50 of low-enthalpy thermal
  energy an use this energy at a higher
  temperature, consume a small amount of high-grade
  energy
• COP
• Recirculation Flow Ratio FR ratio of the mass
  flow rate of the solution leaving the absorber to
  the mass flow rate of working fluid

13
Research on Heat Pumps in México Operating on
Geothermal and Waste Energy as Heat Source
Heat Transformer Type - II Absorption Heat Pump
(HT-HP)
14
Research on Heat Pumps in México Operating on
Geothermal and Waste Energy as Heat Source
Heat Transformer Type - II Absorption Heat Pump
(HT-HP)

• Tests of environmentally friendly working
  fluids
• Previous experimental results for H2O/LiCl,
  H2O/CaCl2 y H2O/CMgCl2 given by Barragán et
  al., 1995 1996a 1996b).
• Further experimental work that the high
  solubility of ZnCl2 was desirable to improve the
  solubility of LiCl and CaCl2 in the solutions
• ZnCl2 was added to the H2O/LiCl, H2O/CaCl2
  experimental binary mixtures to obtain higher
  concentrations and avoid crystallization problems
  
• Results reported by Barragán et al., 1998.

15
Research on Heat Pumps in México Operating on
Geothermal and Waste Energy as Heat Source
Heat Transformer Type - II Absorption Heat Pump
(HT-HP)
Gross temperature lift for the various working
fluids
16

• Investigación sobre Bombas de Calor en México
  Operando con Energía Geotérmica y Calor de
  Desecho
• Conclusiones
• HPs are efficient systems for using and
  upgrading low-enthalpy energy, using relatively
  small amounts of high-grade energy
• GHPs have become the sector of geothermal
  technology with fastest growth in recent years
• Installed capacity increased 730 in the last 10
  years and growth for heating duty increased 500,
  reaching 15,400 MWt 24,300 GWh/yr
• Main developments are in some European countries
  and USA
• Growth is 3 a 4x since 2000
• A substantial amount of RD on HPs using
  geothermal and waste energy has been carried in
  Mexico
• Systems tested include mechanical compression,
  absorption and heat transformer HPs in Mexican
  geothermal fields and in the laboratory
• Results obtained (a) purification of water and
  brines (geothermal) to obtain clean water (b)
  heating, cooling and refrigeration, and (c)
  development of advanced environmentally friendly
  working fluids