The first law of thermodynamics states that the total energy of a system remains constant, even if it is converted from one form to another. Energy also does not distinguish its quality, e.g., 1 Watt of heat equals 1В Watt of work or electricity. Generally, energy exchange is not sensitive to the assumed direction of the process, e.g., energy analysis allows heat to be transferred spontaneously in the direction of the increasing temperature. However, the energy approach has some deficiencies. Such priorities can be carried out based either on the excessive energy consumption, or on the particularly low degree of perfection. Priorities for the required optimization attempts for a system, or its components, can be established. Comparison with the currently achievable values in the most efficient systems is especially important. The degree of perfection in the energy utilization of the process, or its particular parts, allows comparison with the degree of perfection, and the related process parameters, to those in other similar processes. Moreover, like the zeroth law, which provided an impetus for the introduction of the property вЂњtemperatureвЂќ and its clarification, the first law motivates the introduction and helps to clarify the meaning of the elusive concept of вЂњenergy.вЂќД®nergy balance, based on the first law of thermodynamics, is developed to better understand any process, to facilitate design and control, to point at the needs for process improvement, and to enable eventual optimization. However, thermodynamics is a subtle subject, and the first law is much more interesting than this remark might suggest. However much energy there was at the start of the universe, there will be that amount at the end. The first law of thermodynamics is generally thought to be the least demanding to grasp, as it is an extension of the law of conservation of energy, meaning that energy can be neither created nor destroyed. Bahman Zohuri, in Physics of Cryogenics, 2018 5.1 Introduction

Law of entropy