Reverse Carnot Cycle

Japanese: 逆カルノーサイクル - ぎゃくかるのーさいくる

…Therefore, ε _h = Q ₂ / L is an index showing the performance of a heat pump, and is called the coefficient of performance of the heat pump. When T ₁ and T ₂ are fixed, ε _h is at its maximum when the working fluid of the heat pump undergoes the reverse Carnot cycle, which repeats adiabatic compression, isothermal compression, adiabatic expansion, and isothermal expansion. In that case, ε _h = T ₂ / ( T ₂ - T ₁ ), and the larger T ₂ / T ₁ is, the smaller the value of ε _h is (however, the units of T ₁ and T ₂ are K). For example, when T ₁ = 273K and T ₂ = 318K, ε _h ≒ 7, and ideally, the amount of heat pumped is equivalent to 7 times the work input. …

From [Freezer]

...In a refrigerator or heat pump that takes heat Q ₁ from a heat source (a space or object with a large heat capacity) at temperature T ₁ (K) and gives heat Q ₂ to a heat source at temperature T ₂ (K) ( T ₁ 〈 T ₂ ), the ideal cycle that maximizes the coefficient of performance is a reversible cycle that starts with adiabatic compression, repeats isothermal compression, adiabatic expansion, and isothermal expansion, and absorbs heat during isothermal expansion and releases heat during isothermal compression. This cycle is the Carnot cycle in the reverse direction, and is called the reverse Carnot cycle. In this case, Q ₁ / T ₁ = Q ₂ / T ₂ holds, and ε _r and ε _h are given by ε _r = T ₁ /( T ₂ - T ₁ ) and ε _h = T ₂ /( T ₂ - T ₁ ), respectively. ...

*Some of the terminology that refers to the "reverse Carnot cycle" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…したがってε_h＝Q₂/Lは熱ポンプの性能を示す指標となり，これを熱ポンプの成績係数という。T₁,T₂が定まっているときε_hが最大となるのは，熱ポンプの作動流体が行う変化が断熱圧縮，等温圧縮，断熱膨張，等温膨張を繰り返す逆カルノーサイクルの場合であって，そのときε_h＝T₂/(T₂－T₁)となり，T₂/T₁が大きいほどε_hの値は小さくなる(ただし，T₁,T₂の単位はK)。例えば，T₁＝273K，T₂＝318Kの場合，ε_h≒7であり，理想的には仕事入力の7倍に相当する熱量をくみ上げられることになる。…

【冷凍機】より

…温度T₁(K)の熱源(熱容量の大きな空間や物体)から熱量Q₁を奪って温度T₂(K)(T₁〈T₂)の熱源に熱量Q₂を与える冷凍機あるいは熱ポンプにおいて，成績係数が最大となる理想的サイクルは，断熱圧縮から始まって等温圧縮，断熱膨張，等温膨張を繰り返し，等温膨張の間に吸熱，等温圧縮の間に放熱を行う可逆的なサイクルである。このサイクルは，カルノーサイクルを逆方向に行わせたものであり，逆カルノーサイクルと呼ばれる。このときQ₁/T₁＝Q₂/T₂が成り立ち，ε_rおよびε_hはそれぞれε_r＝T₁/(T₂－T₁)，ε_h＝T₂/(T₂－T₁)で与えられる。…