In the heat source system, the absorbed environmental heat flows to the evaporator. There it encounters the liquid refrigerant. This refrigerant evaporates even at very low temperatures. This allows the heat pump to absorb heat from the environment even in frosty conditions. The refrigerant absorbs heat from the environment and becomes gaseous.
Ako funguje tepelné čerpadlo
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Ako funguje tepelné čerpadlo?
Tepelné čerpadlo funguje podobne ako chladnička – len v opačnom garde. Zatiaľ čo chladnička odoberá tepelnú energiu z potravín, t. j. z vnútra chladničky, a odvádza ju von, tepelné čerpadlo postupuje opačne: odoberá tepelnú energiu z prostredia mimo budovy a využíva ju na vykurovanie interiéru. Okrem vnútorného alebo vonkajšieho vzduchu dokáže tepelné čerpadlo využívať tepelnú energiu aj z podzemnej vody a zeme. A keďže teplota získaného tepla zvyčajne nepostačuje na vykurovanie budovy alebo teplej úžitkovej vody, na zvýšenie teploty sa používajú termodynamické procesy.
Important facts at a glance:
- A heat pump extracts up to three quarters of the energy it needs from the environment (air, ground, or water) and only one quarter from electricity.
- The core components are the evaporator, compressor, condenser, and expansion valve, which work together in a closed circuit.
- Heat pumps function reliably even at very low outdoor temperatures and can be used to cool rooms in addition to heating them.
Structure and operating principle of the heat pump
Regardless of the tapped environmental energy source, the heat pump system consists of three parts:
Heat source system: extracts energy from the environment
Heat pump: Makes environmental heat usable
Heat distribution and storage system: distributes and stores heat in the building
Proces chladivového okruhu – podstata princípu tepelného čerpadla
Bez ohľadu na to, ktorý zdroj tepla sa používa na výrobu tepla, súčasťou pracovného režimu tepelného čerpadla je vždy proces chladivového okruhu, ktorý má štyri kroky.
The refrigerant, now in gaseous form, enters the compressor. This requires electricity and greatly increases the pressure of the gas. The increase in pressure also raises the temperature of the gas to the level required for heating. The compressor is the central component that uses electrical energy to convert environmental heat into usable heating energy.
Interesting fact: This principle can be observed not only in the functioning of heat pumps. If the opening of a bicycle pump is closed and the air is compressed, the cylinder of the air pump heats up.
The hot, gaseous refrigerant flows into the condenser. There, it releases heat to the heating system by warming the heating water. During this process, the gas cools down and becomes liquid again. The released heat energy is then distributed to the rooms via the heating distribution system (e.g., underfloor heating). Some of it can also be stored in a buffer or hot water tank for later use.
The refrigerant, which is now liquid again but still under pressure, is passed through an expansion valve (also known as a pressure relief valve). This causes the pressure to drop significantly, the refrigerant cools further, and the entire heat pump process begins again.
Druhý výmenník tepla (kondenzátor) potom odovzdáva energiu z ohriatej pary do vykurovacieho okruhu (podlahové vykurovanie, radiátory, vykurovací zásobník a/alebo zásobník na teplú vodu). Chladivo, ktoré je stále pod tlakom, sa pritom ochladí a opäť skvapalní. Predtým, ako môže prúdiť späť do okruhu, sa chladivo najprv rozšíri v expanznom ventile. Keď dosiahne svoj pôvodný stav, chladiaci cyklus sa môže opäť spustiť.
Princíp tepelného čerpadla na príklade vzduchového tepelného čerpadla
Najjednoduchšie je vysvetliť tento proces na príklade tepelného čerpadla so vzduchovým zdrojom: vzduchové tepelné čerpadlo môže pozostávať z jednej alebo dvoch jednotiek. V oboch prípadoch zabudovaný ventilátor aktívne nasáva okolitý vzduch a smeruje ho do výmenníka tepla. Cez výmenník tepla prúdi chladivo, ktoré pri veľmi nízkych teplotách mení svoj fyzikálny stav. Keď sa chladivo dostane do kontaktu s okolitým vzduchom, zohreje sa a postupne sa stáva parným. Na zvýšenie vzniknutého tepla na požadovanú teplotu sa používa kompresor. Tým sa para stlačí a zvýši sa tlak aj teplota pár chladiva.
Neustále opakovanie procesu
Tieto procesy prebiehajú v uzavretom okruhu v tepelnom čerpadle. Na prenos tepla sa používa kvapalina (chladivo), ktorá sa odparuje pri veľmi nízkych teplotách. Na odparovanie tejto kvapaliny sa používa tepelná energia, napríklad zo zeme alebo z vonkajšieho vzduchu. Na dodanie energie postačujú aj teploty mínus 20 stupňov Celzia. Chladná para chladiva, napríklad -20 stupňov Celzia, sa potom vysoko stlačí. Pritom sa zohreje až na teplotu 100 stupňov Celzia. Tieto pary chladiva sa kondenzujú a uvoľňujú teplo do vykurovacieho systému. Následne sa výrazne zníži tlak kvapalného chladiva. To spôsobí, že teplota kvapaliny klesne späť na pôvodnú úroveň. Proces sa môže začať od začiatku.
Refrigerant: Essential for the heat pump to function
A special refrigerant is essential for a heat pump to function. A key feature is its extremely low boiling point. This allows the liquid to turn into a gas even at very low temperatures – sometimes as low as minus 20 °C. This is why a heat pump works reliably even in winter when outside temperatures are low.
Incidentally, the latest generation of Viessmann heat pumps use the natural refrigerant propane (R290), which is in no way inferior to conventional refrigerants in terms of its properties.
Kompresia si vyžaduje elektrický prúd
Základnou súčasťou chladivový okruhu je kompresor. Bez kompresie sú totiž výstupné teploty príliš nízke na to, aby dokázali vykurovať budovu na príjemnú teplotu o to viac počas veľmi chladných dní s dvojcifernými mínusovými teplotami.
Heat pump for heating and cooling
The heat pump functions reliably even at very low outdoor temperatures. Water-to-water and brine-to-water heat pumps are particularly efficient at supplying heat, as the ground and groundwater maintain constant temperatures throughout the year. However, air-to-water heat pumps also operate at temperatures below freezing. Viessmann heat pumps, such as the Vitocal 250-A, remain reliable even at low outdoor temperatures (below -10 °C).
Thanks to their reversible function, heat pumps can also cool in summer
The operating principle of a heat pump is reversible. This means that rooms can not only be heated, but also cooled with a heat pump, provided that the technical requirements are met. There are two different cooling methods:
- Natural cooling: The heat pump remains switched off. The cooler temperature of the environmental heat source (ground, groundwater) is used to cool the rooms via a heat exchanger.
- Active cooling: The function of the heat pump is actively reversed so that the heat is transported from the rooms to the outside. This mode of operation is similar to that of a refrigerator.
You can read about the detailed process of the cooling functions in our guide to natural and active cooling.
Reversing the function of the heat pump for cooling
The principle of operation of the heat pump is reversible. For this reason, rooms can not only be heated, but also cooled - if the technical requirements are met. A distinction must be made between Natural and Active Cooling. While in the latter the function of the heat pump is actively reversed, it remains switched off in passive or natural cooling.
FAQ – Frequently asked questions about how heat pumps work
The power consumption of a heat pump depends, among other things, on its efficiency (annual performance factor) and the required heating capacity. Most of the heating energy comes from the environment; the electricity is mainly needed to operate the compressor.
Yes, most modern heat pumps can generate hot water for the household in addition to heating rooms. There are also standalone hot water heat pumps specifically designed for hot water production, which efficiently heat drinking water all year round. These can either use exhaust air from the house (e.g., from the basement or laundry room) or extract heat from the outside air. You can find out more about this special type of heat pump in our guide to hot water heat pumps.
Yes, Viessmann offers heat pumps that reach high flow temperatures (e.g., 70 °C) and can therefore also be used in well-insulated existing buildings with conventional radiators.
You can read more about this in our guide to heat pumps in older buildings.
The combination of a heat pump and a PV system is ideal. The solar power generated during the day can be used directly to operate the heat pump, which further reduces operating costs and increases independence.
A geothermal heat pump uses the heat stored in the ground. There are two main methods used for this:
- Ground probes: These are drilled vertically up to 100 meters deep into the ground. They require little space and are particularly efficient.
- Ground collectors: These are laid horizontally and over a large area at a shallow depth. They are cheaper to install but require a larger garden area.
The most suitable method depends on the conditions of your property. You can find more details in our guides to ground collectors and geothermal probes.
V praxi sa používa viacero kompresorov vrátane piestových alebo špirálových, ktoré sú poháňané elektricky. Spotreba energie na kompresiu závisí od mnohých faktorov. Patrí medzi ne potreba tepla, technológia kompresora a v neposlednom rade teplotný rozdiel medzi zdrojom tepla a vykurovacím systémom. Všeobecne platí pravidlo: čím väčší je teplotný rozdiel medzi zdrojom tepla a teplotou prietoku, tým viac musí kompresor pracovať.
