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HISTORY AND LATEST TRENDS OF
DOMESTIC HOT WATER HEAT
PUMP TECHNOLOGIES
2019.08.27
JAPAN NATIONAL TEAM
WASEDA University Kiyoshi Saito
International congres of refrigeration, August, 24-30, 2019
INTRODUCTION
2
Heat pump technologies are promising ones to reduce CO2 emissions.
Recently new technologies appeared for DHW heat pump technologies
I would like to introduce the followings.
1. History of development – How systems have changed?
2. Components and system technologies
3. Kinds of refrigerant
4. End-user and installer focused technologies
5. Water quality and saving management technologies
6. Smart technologies(ZEB, smart grid, smart energy)
International congres of refrigeration, August, 24-30, 2019
MARKET OF HEAT PUMP SYSTEMS
3
In Japan,
2001: CO2 refrigerant heat pump system was
started to put on market
2018: 6 million systems were going into
market.
Figure: Development of hot water heat pumps sales in Switzerland
In Switzerland,
1919 - 1950: heat pumps for space heating and
domestic hot water heating were developing
from rare first prototypes to a reliable,
efficient and even economically viable
heating device.
2009-2015: the sales numbers of hot water heat
pumps has increased from 364 in 2009 to
4919 units in 2015.
Figure: Development of hot water heat pumps sales in Japan
International congres of refrigeration, August, 24-30, 2019
HEAT PUMP CYCLE
4
200 300 400 500600
700
800
900
1000
2000
3000
4000
5000
6000
60
Specific enthalpy kJ/kg
Pre
ssu
re k
Pa
T = 0 oC
4020 80 100
R 410A1
23
4
Conventional Freon system CO2 system
Condenser
Compressor Expansion Valve
Evaporator
Gas cooler
Compressor Expansion Valve
Evaporator
International congres of refrigeration, August, 24-30, 2019
COMPONENT TECHNOLOGIES
5
R134a miniature turbocompressor
Figure 20: Oil free miniature turbo compressor, Left: 3D flow simulation, Middle: Manufactured impeller with 20
mm diameter, Right: Compression unit with impeller, bearings and electromotor (Schiffmann 2005).
Two-phase compressor
Figure 21: Left: T-s diagram of R290 (propane) as an example, illustrating the process with the two-phase compressor
(evaporation temperature 0°C, condensation temperature 40°C), a conventional compressor and an ideal Carnot
process, Right: CAD model of the compressor test stand (Friedl et al. 2012).
International congres of refrigeration, August, 24-30, 2019
COMPONENT TECHNOLOGIES
6
Development of DENSO Development of MITSUBISHI
New compressor for CO2 refrigerant
International congres of refrigeration, August, 24-30, 2019
COMPONENT TECHNOLOGIES
7 DAIKIN
Water side heat transfer enhancement for CO2 gas cooler
International congres of refrigeration, August, 24-30, 2019
COMPONENT TECHNOLOGIES
8
MITSUBISHI
ELECTRIC
New gas cooler
International congres of refrigeration, August, 24-30, 2019
COMPONENT TECHNOLOGIES
9 DENSO
Ejector with flow control
International congres of refrigeration, August, 24-30, 2019
COMPONENT TECHNOLOGIES
10
"Uretank"
Changes in the hot water storage unit of Hitachi's Eco Cute
Glass wool Styrofoam Styrofoam
+ vacuum
insulation material
※Standard type
Urethane foam
Urethane foam + vacuum
insulation material
※Mainly high-efficiency type ※High-efficiency type
2003 ~ 2007 ~ 2012 ~ 2014 ~
History of thermal storage tank development
To prevent legionella, we have to heat up to more than 65 ℃. That’s why insulation of thermal storage is very important.
International congres of refrigeration, August, 24-30, 2019
SYSTEM TECHNOLOGIES
11
Solar assisted system
International congres of refrigeration, August, 24-30, 2019
SYSTEM TECHNOLOGIES
12
Fig. Hybrid system with Gas heater
Hybrid system with gas water heater
International congres of refrigeration, August, 24-30, 2019
SYSTEM TECHNOLOGIES
13
Compact Thermo Acoustic Heat Pump for the Built Environment (CTWB)
Project goal is to develop a prototype compact TAWP
for decentralized heating and cooling of buildings with
a COP of 3.5 to 4.0 (air / water) and a thermal capacity
of 1kW. This contributes to compact, inexpensive and
efficient developments in the field of heat pump
technology in the built environment.
Blue Heart heat pumps are closed systems that are
filled with Helium under pressure.
Electrical driven drivers send an acoustic wave
through the pump.
At the point where Helium is compressed heat is
exchanged by a heat exchanger.
Between the two heat exchangers a regenerator is
located. Within the regenerator a thermal cycle arises.
In this way the regenerator creates a temperature
difference or a so called thermal pump or heat pump.
At the point where the helium is expanded, heat from
the source is added using a second heat exchanger.
The heat exchangers (2) and (4) are connected to either
the source or heatsink, depending on the demand of the
consumer. Either heating or cooling.
International congres of refrigeration, August, 24-30, 2019
SYSTEM TECHNOLOGIES
14
Prediction
of demand
Prediction of
solar energy
Optimum control of
battery and heat pump
Battery
Heat pump
Thermal storage
Grid
Demonstration Image of the project
International congres of refrigeration, August, 24-30, 2019
SYSTEM TECHNOLOGIES
15
Absorption and adsorption technologies
International congres of refrigeration, August, 24-30, 2019
REFRIGERANTS
16
• In most of the countries, R410a, R134a, R407c were used for
DHW heat pump.
• In Japan, refrigerant of most of DHW is CO2. Recently, R32 and
HC(R290) system has been just put on market.
• Recently, HFOs are investigated for the refrigerants of DHW heat
pump
International congres of refrigeration, August, 24-30, 2019
END-USER FUCUSED TECHNOLOGIES
17
Multi function type
Hot water supply + floor heating + space heating
Floor
heating
International congres of refrigeration, August, 24-30, 2019
END-USER FUCUSED TECHNOLOGIES
18
Figure 23: Left: New components of the wall unit THERMOS, Right: Renovated
bathroom with integrated wall unit THERMOS (Swissframe AG) (Büchel et al. 2016).
Front wall installation system in bathroom
International congres of refrigeration, August, 24-30, 2019
INSTALLER FOCUSED TECHNOLOGIES
19
A plug and play concepts for existing and new
domestic buildings. A special integrated unit has been
developed combining heat pump technologies with
solar energy.
The complete installation is built pre-fab at the
factory, avoiding potential installation failures with
‘new technologies’.
International congres of refrigeration, August, 24-30, 2019
WATER QUALITY MANAGEMENT TECH.
20
Bubble cleans up piping between heat pump and bathtub
International congres of refrigeration, August, 24-30, 2019
WATER SAVING TECHNOLOGIES
21
With a classic shower, 10 minutes of showering
takes about 70 to 90 litres of water. The water
used during showering corresponds
approximately to 30% of the total water use.
The rain shower grows in popularity as comfort
shower in modern bathrooms, but a rain shower
uses 15 to 30 litres per minute! By recirculation
more than 85% less water and thus 70% less
energy is used. Each drop is recycled 9 times
via a unique system that cleans water based on
UV light
International congres of refrigeration, August, 24-30, 2019
SMART TECHNOLOGIES
22
HEMS controller controls heat pump water heater, air-conditioner, lights, refrigerator
and so on simultaneously - 16 systems can be connected -.
International congres of refrigeration, August, 24-30, 2019
CONCLUDING REMARKS
23
The recent R&D of heat pump system are introduced.
Especially in Japan, to develop DHW heat pump that uses CO2 as a
refrigerant, many new technologies appeared.
From now, still some developments of new technologies will be
needed for DHW heat pump. For example,
• Smart use of DHW heat pump with other systems in domestic use.
• DHW heat pump that self-consumes solar energy optimally.
• DHW heat pump that uses lower GWP refrigerants but whose cost
is lower
Anyway, heat pump technologies contribute a lot to reduce the CO2
emissions. We have to do our best to expand this technologies.
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