This cooler box is designed to assist humans in getting cold drinks when traveling long distances by car. Semi-conductor cooler box components consist of TEC1-12706 and TEC1-12715, styrofoam box with a size of 53 × 31 × 43 cm, copper and aluminum processor heatsinks, fans with 12V and 1A voltage, acrylic, and retaining bolts. The lowest temperature that can be achieved by TEC1-12706 and TEC1-12715 is 23.7 • C which is reached in 60 min. The efficiency possessed by TEC with a heatsink 77.8%. Maintenance for the semi-conductor cooler box is very easy by not using a voltage that exceeds 12 V and it is not expected to disassemble the cooling component circuit consisting of the heatsink and TEC.

Covid 19 cases that have begun to decline to the government's policy of loosening the wearing of masks in open spaces, do not mean that Covid 19 has disappeared from Indonesia. A healthy environment is something we still need to maintain in this post-Covid 19 pandemic era. The partner in this activity, namely the An-Nur Mushola Management, needs education about the sterilization of places of worship because the location is right on the edge of the highway which is crowded with activities coupled with the location of the Mushola which is adjacent to the kindergarten (Kindergarten) and elementary school (elementary school) this is clearly related to the health and safety of the pilgrims and also the students in the environment. Currently, the management of the Place of Worship really hopes for assistance in the form of health protocol facilities and education on the implementation of sterilization. Based on the explanation from the partner, the main needs during this pandemic are knowledge about the manufacture of disinfectant liquids, how to implement health protocols, and the disinfection process of the place. Based on the problems faced by the partners, researchers through community service activities entitled "PKM Making Disinfectants as an Effort to Maintain the Post-Pandemic Environment" will help partners provide solutions related to the problems faced. The target to be produced from the implementation of this program is to provide education related to how to make disinfectant liquids in an effort to maintain a healthy environment after the Covid-19 pandemic.

Heat exchanger adalah suatu alat penukar panas paling umum digunakan yang berfungsi sebagai pemanas maupun pendingin, dimana proses pertukaran panas yang terjadi pada heat exchanger disebabkan adanya perbedaaan temperatur. Semakin lama heat exchanger digunakan akan menyebabkan terjadinya fouling (pengotoran) di bagian dalam heat exchanger. Semakin besar fouling yang terjadi akan menyebabkan terjadi penurunan kinerja heat exchanger seperti besarnya laju perpindahan panas aktual dan efektivitas. Oleh karena itu dilakukan analisis heat exchanger untuk mengetahui pengaruh fouling terhadap laju perpindahan panas aktual dan efektivitas heat exchanger. Pada penelitian ini tipe heat exchanger yang digunakan adalah jenis shell and tube, spesifikasi alirannya adalah counter flow, one pass, dengan baffle bertipe singgle segmental, fluida yang digunakan adalah Sollar pada shell dengan suhu masuk 536 °F ke 248 °F dan fluida minyak mentah pada tube dengan suhu masuk 95 °F ke 208,4 °F. Berdasarkan hasil perhitungan, tahanan panas dalam keadaan bersih didapatkan (UC) 157.42 BTU/ jam.ft2.oF, sedangkan tahanan panas dalam keadaan kotor (UD) sebesar 9.28 BTU/ jam.ft2.oF  sehingga didapatkan Nilai Faktor Pengotoran ( Rd )  sebesar 0,101 dan nilai effektifitas alat penukar kalor tipe shell and tube sebesar 63,48 %.Kata kunci— Alat penukar kalor, Shell and tube, Faktor Pengotoran, Effektifitas.

The utilization of wind turbines is able to convert wind energy into electrical energy. It is recorded from the DG of NREEC source that Indonesia has a wind energy potential of 60.6 Giga Watt (GW) with a total renewable energy potential of 442GW. One of the most common types of wind turbines is the horizontal axis wind turbine. This study uses a literature study method that aims to compare and summarize data optimizing variations in the number of blades and wind speed on horizontal axis wind turbines from various sources. The results of the study are known that the pinwheel power generated by the rotation of the pinwheel blade produces energy that is converted into electrical energy. The wind speed and blade rotation yield are directly proportional to the energy produced. The greater the wind speed given to the turbine, the higher the rotation. Variations in the number of blades result in variations in rotational properties, since the effect of the ratio of tip speed is inversely proportional to wind speed. The performance of horizontal axis wind turbines can be optimized by applying blade design using chord and twist linearization methods. The greatest efficiency of the counter-rotational horizontal shaft wind turbine is achieved at a blade angle of 10° and a wind speed of 4.03m/s, resulting in a maximum efficiency of up to 71.8%, which is higher than the optimal single-rotor power coefficient of 59%. This means dual-rotor wind turbines are more efficient at converting energy than single-rotor wind turbines.