Heat pumps for heating and cooling
Alojz Poredoš ... [et al.]
2018, 1. izd.
[VI], 199 str.
ISBN 978-961-6980-46-3
Enotna cena: 15,00 €
Table of Contents
1 Introduction ......................................................................................................................... 1
1.1 The importance of heating and cooling ................................................................... 2
1.2 The definition of a heat pump ................................................................................. 2
1.3 A brief discussion on the thermodynamics of heating and cooling with
heat pumps............................................................................................................... 3
1.3.1 Exergy and anergy of heating and cooling .......................................................... 7
2 Thermodynamics and characteristics of vapour-compression heat pumps ....................... 11
2.1 Carnot heat-pump cycle ...........................................................................................11
2.2 Compressor-driven vapour-compression heat-pump cycle .....................................14
2.2.1 Heat-pump device with an expansion element .................................................. 15
2.2.2 Suction of dry refrigerant vapour ....................................................................... 16
2.2.3 Subcooling ......................................................................................................... 18
2.2.4 Superheating ...................................................................................................... 21
2.2.5 Internal regeneration of heat .............................................................................. 22
2.2.6 Polytropic compression ...................................................................................... 24
2.3 Coefficient of the performance and exergy efficiency of vapour-
compression refrigerators and heat pumps ............................................................ 26
3 Thermodynamics and characteristics of sorption refrigerators and heat pumps .................. 30
3.1 An introduction to the thermodynamics of sorption refrigerators and
heat pumps .......................................................................................................... 30
3.2 The thermodynamics of absorption refrigeraton and heat pumping ........................ 33
3.2.1 The thermodynamic cycle of single-stage absorption refrigerators and
heat pumps ......................................................................................................... 34
3.2.2 The thermodynamic cycle of double-stage absorption refrigerators
and heat pumps .................................................................................................. 39
4 Heat-pump elements and their characteristics .................................................................... 42
4.1 Compressors ........................................................................................................... 42
4.1.1 Positive-displacmenet compressors: Reciprocating (piston)
compressors ....................................................................................................... 42
4.1.2 Positive-displacmenet compressors: Screw compressors ..................................46
4.1.3 Positive-displacement compressors: Compressors with rotary pistons:
Roll ing Piston or Stationary-Vane Rotary Compressor ...................................... 47
4.1.4 Positive-displacement compressors: Compressors with rotary pistons:
Rotary-Vane Compressor ................................................................................... 48
4.1.5 Positive-displacement compressors: Rotary-scroll compressors ........................ 49
4.1.6 Rotary centrifugal (turbo) compressors ............................................................... 50
4.1.7 Volumetric efficiency of piston compressors ........................................................ 51
4.2 Evaporators/Condensers ......................................................................................... 51
4.2.1 Boiling .................................................................................................................. 52
4.2.2 Condensation ....................................................................................................... 54
4.2.3 External (outdoor) units of condensers or evaporators (air-to-refrigerant) ........... 56
4.2.4 Compact (indoor) units of condensers or evaporators (water-to-refrigerant)........ 57
4.2.5 Shell-and-tube units of evaporators and condensers .......................................... 58
4.2.6 Throttling/Expansion devices ............................................................................... 59
4.2.7 (De)Frosting process ........................................................................................... 61
4.2.8 Reverse operation of the heat pump .................................................................. 62
5 Refrigerants ........................................................................................................................... 66
5.1 Environmental, safety and chemical-stability properties ......................................... 69
5.1.1 Ozone Depletion Potential (ODP), Global Warming Potential (GWP)
and Total Equivalent Warming Index (TEWI) ...................................................... 69
5.1.2 Toxicity and flammability ..................................................................................... 70
5.1.3 Chemical stability of refrigerants ......................................................................... 72
5.2 Thermodynamic and thermo-physical properties ..................................................... 72
5.3 Future heat-pump refrigerants .................................................................................. 73
6 Heat sources and types of heat pumps .................................................................................. 75
6.1 Air source heat pumps (types and performance) ..................................................... 81
6.1.1 Air-water hydronic heat-pump systems ............................................................... 82
6.1.2 Air-air refrigerant circuit heat-pump systems ...................................................... 89
6.2 Water-source heat pumps (types and performance) ................................................91
6.2.1 Water-water hydronic heat pumps (types and performance) ..............................93
6.2.2 Water-air refrigerant circuit heat pumps (types and performance) ..................101
6.2.3 District heating/cooling with heat pumps ........................................................... 102
6.3 Ground-source and geothermal heat pumps (types and performance) .............109
6.4 Assisted heat pumps with different heat sources ................................................... 116
6.4. I Types ofheat pump's operation modes .............................................................. 118
6.4.2 Solar-assisted heat pumps ............................................................................... 120
6.4.3 Gas- or biomass-assisted heat pumps ............................................................. 126
6.4.4 Compact hybrid heat pumps ............................................................................ 127
6.4.5 District-heat-assisted heat pumps .................................................................... 127
7 Thermal storage and sanitary hot-water tanks .................................................................. 128
7.1 Short- and medium-term thermal storage systems .............................................. 132
7.1.1 Sanitary water and residential buffer storage tanks ......................................... 132
7.2 Long-term seasonal thermal storage ................................................................... 140
8 Internal heating systems .................................................................................................... 144
9 Dimensioning of heat pumps ............................................................................................. 150
9.1 System design requirements ................................................................................ 150
9.2 Dimensioning the heat-pump system ................................................................... 152
9.2.1 Design transmission heat loss for a heated space .......................................... 153
9.2.2 Internal design temperature ............................................................................. 156
9.2.3 Climate data ..................................................................................................... 157
9.2.4 Design ventilation heat loss for a heated space ............................................... 157
9.3 Sizing heat-pump capacity for sanitary hot water .................................................. 158
9.4 Dimensioning the heat source of the heat-pump system ....................................... 161
9.4.1 Air heat-source .................................................................................................. 161
9.4.2 Underground water heat source ........................................................................ 162
9.4.3 Ground source - soil heat exchanger. ................................................................ 163
9.4.4 Ground source - borehole heat exchanger. ....................................................... 168
9.4.5 Surface water source - heat exchanger. ............................................................ 171
9.5 Dimensioning of the circulation pump ..................................................................... 172
9.6 Calculation of the total electrical energy consumption for electrically
driven heat pumps ................................................................................................... 175
9.6.1 Meteorological data ............................................................................................. 175
9.6.2 Energy consumption calculation ......................................................................... 176
9.6.3 Heat-energy requirement for space heating ....................................................... 177
9.7 Seasonal performance factor ................................................................................. 181
10 The economics of heat pumps ........................................................................................ 188
10.1 The return on investment (ROI) ......................................................................... 189
10.2 Net present value (NPV) .................................................................................... 191
10.3 Operating life expectancy of devices ................................................................. 192
